Confused about my career need guidance to enter in IT field

Mechanical Engineering course is an evergreen subject and there are very good chances for these engineers. You have already put in very good service and with the experience, you have now you should think of shifting from the present company to a better company. The MNC and many other industries are paying very good pay packets to these engineers. Think in these lines.
Concentrate on GATE. If you get a good score in that you will get very good jobs in many government organisations and R&D institutes and MNCs. Then you will have a very good future. This is one option you can think of.
Another point is if you want to join an IT industry now your expereince will be not counted. Many good IT companies go for freshers or one-year-old passed outs. So getting in a good company of It is a very very difficult proposition. You have to start from scratch and you have to join a small company and struggle hard to get into the grew and then you have to try for a good company after putting in some good experience. So think twice.
Still, if you feel that you should go for an IT job try to do some certification courses like SAP, ERP or tally and try one or two languages and then start applying for the jobs all the best to you.

You are already having a job in Mechanical Engineering line. Now you have an inclination to switch to IT or computer line. This is alright but what is the main thing that is driving you to think so. Is it the earning potential of IT people or your interest in IT area. The answer of this question is required to know whether you are really interested in IT line or simply fascinated by it. Anyway, I assume that you have a liking for IT area and you are also stagnated in your present job and do not see much prospects of growth there. It will also matter at this stage that how much computer awareness you have as regards to knowledge of computer languages and other computer application being used in mechanical engineering work. For a mechanical engineering graduate there are scope in IT area in mechanical designing and concerns of mechanical parts used in robotics and automation industry. But that will again be confined to the mechanical stream. So, we have to think of some certificate course or diploma course after which you can enter the computer industry. So there are some options and these are as follows. These are not merely an option but good from job point of view also in today's market -

1. Data Science - It is one of the emerging area and requires mining of data, assembling it and presenting it in a business format where it is useful for decision making. It requires a good academic background and one will have to learn the computer language like Python or equivalent and should have the knowledge of basic computer skills like MS office and basic graphic skills. There are courses on Data Science available in internet and basic courses are free of charge also.

2. Networking and Security - This is slightly a specific area but very interesting and rewarding if one can get experience in it. One will have to go through a diploma or certificate course in this from a good computer institute and then can apply in the industry. Everyone today wants the safety of their computer system from cyber attacks.

3. Digital Marketing - This is also becoming a lucrative area and one does not require high computer skills for it but it is also a rewarding field. It is more related to marketing in the digital arena as everyone is having a handheld device with him where a company can always present its product to the user. One will have to do a course in digital marketing from some institute if one has a liking for this business marketing course.

4. Data Management - This also does not require high skills in computer sciences. For this, one will have to go through some course in Data Management and generally this course will enable one to manage the data, navigating the data, designing and planning of database, managing client accounts etc. There are softwares available in the organisations to cater to these and one has to use them as needed.

In addition to above, there are some courses which are general in nature and I have not recommended them above as you are not from the computer science background but yes, if you feel interested it is not a bad idea to go through them also at an opportune time to enhance skills in the IT area. These are web designing, 3D printing, animation, software testing, system management, networking, artificial intelligence, cloud computing etc.

Most of the MNC companies recruit freshers for the IT jobs because of two obvious reasons -
1) Freshers are inclined to learn the more in the training period since they can anticipate growth after the training in the IT field.
2) Their untiring stamina to understand the complexities of the given situation and to exercise the different concepts to get the maximum out put in the given situation.
However, this alone is not the case with the freshers and even the aspirants having sufficient exposure in other fields can exhibit such qualities but they are guided by certain rules for recruitment ie a candidate must be a fresher having passed in Engineering in any branch with a minimum scoring of 65 percent in each semesters and the year of passing should not exceed beyond a year.
You are not fitting in such a criteria and hence the possibility of entry in IT field seems to be remote. At this stage, you can try to have certification in SAP, ERP, Oracle etc to enhance your employability status in the IT field. Start looking out the jobs in a medium sized company. Your recruitment would depend upon your comprehension in the newly learnt domain apart from your excellent communication- skill exhibited by you before the Board of interview.
That would be starting phase of your career in the IT field and further channel of promotion in the major IT companies can be achieved with your exposure in this field within two to three years.
Prior to switching over to IT field look for the prospects in your own area and qualifying GATE would offer you an advantageous point in case you change your organisation. With the accumulation of experience of five odd years, your demand in this field would surge in a huge way.

Nowadays, all the engineering domains are interlinked and that's the reasons that mechanical engineers are taught computer programming and languages in the initial period of course.
Mechanical engineers are sitting in the placement exams organized by IT companies like TCS.
So, there is no hard and fast rule for the same.
If you are really willing to switch to IT sector leaving your current job please note that your experience will not be counted here. In fact, to find a job will also be difficult for you. You may join some refreshment course in any of the demanding IT related topics of your interest like Autosys. The organizations providing such courses mostly give job assurance after successfully completing the course as they have a tie-up with companies.
So, you may get a job, but further progress will depend solely on your performance and dedication only. For that, you must have an interest and in-depth knowledge in that field.
All the best!