Father's Name have space in 10th and 12th but no space in B. Tech. Marksheet

If the name is correct and only the problem is a space between the words and that too in your B.Tech certificate, it is very easy to get it corrected by applying to the university in which you have studied. Some universities are having an online application facility is also there. You can upload all the required documents with the necessary fees and application. If the online facility is not there you have to apply manually through the college you have studied. The university will arrange for the correction and will send you back the corrected certificate.
As it is only a space in between the names it may not be a major problem but it is better always to get it corrected.

If your all the documents have similar father's name I will suggest you contact the principal of your college for the correction in B. Tech mark sheet. He will suggest you for the complete procedure and the nominal fees which are taken by the university for the name correction.
Some universities also provide online facilities for the name correction. You principal will guide you whether online facility for the particular university is available or not. In an online facility, you have to submit an online form with relevant documents like adhaar card, mark sheet of 12 class, photocopy of TC, etc. You have to pay online fees through any digital medium.
In offline mode, your principal will provide you with a form. You have to fill up the form and submit the form along with relevant documents and challan for the fees.
After that, your principal will forward your application to the university and you will be provided with a new corrected mark sheet.

From your query it is not very clear whether the name of your father is incorrect in your B Tech marksheet or in 10th and 12th class certificates.

Anyway, if it is incorrect in B Tech mark sheet then you have to apply to the University for this correction. There may be a specific application form for this and you may have to pay a fee for getting the corrected marksheet.

You have to enclose the copy of authentic document like PAN card or aadhaar card of your father to give the reference of correct name to the university authorities so that they can incorporate the same in the corrected copy of marksheet.

On the other hand if there is problem in your 10th and 12th certificates then you have to apply to the education board for the necessary correction following the usual procedure.

There may be a small mistake in the name but it has to be got corrected to avoid any inconvenience and embarrassment at the time of verification of documents when you attend interview.

Relax. Most places middle name is optional. Still you need to correct it to show both certificate and marksheet belongs to same person. If your graduation certificate has match with 12th certificate then you are good , no need to worry about anything. If not then check your university site for requesting rectification in name. If website don't have option then visit university and fill form for rectification. Most likely they will issue duplicate marksheet with corrected name. Last option is to make affidavit with proofs that both certificates and mark sheets belongs to same person.

In your B.Tech certificate, spacing has not been maintained while indicating your name and surname. This is not a major issue and can be rectified by the university in case you approach to the university for the correction.
You will be required to fill up a form indicating the discrepancy with the prescribed fee for this purpose in the form of Demand - draft along with the photo- copies of 10 th and 12 th certificate. Get your form forwarded by the Principal of your college from you have passed.
On receipt of your request, the university will release a duplicate certificate free from discrepancy.
The other way is to approach a lawyer in the office of Rotary - magistrate for the affidavit so that the discrepancy is removed. He will do the needful. You need to produce the photo - copies of Aadhar - card, 10 th, 12th certificate and also the recently passed B.Tech certificate.
After you secure the affidavit having been signed by Magistrate, get the same published in news paper including one in local news paper. Preserve these so as to produce during the stage of verification.