Can a rusted pen drive be cleaned and re-used?

First of all, I feel it is risky to use a rusted pen drive as it is risky. If the damage of this pen drive is very high it may damage your laptop or desktop also. These days the pen drives are available at a very low cost. I feel you can go for a new one.
But there are ways and means to clean rusted pen drives. There are some organic liquids which are very good stain cleaners and rust removers.
I suggest one or two chemicals which are good for rust cleaning. The first one is trichloroethylene. This is a very commonly available laboratory chemical. This is having some industrial uses also. But the chemical is banned for industrial use due to its pollution problems. But small quantities for lab use are available. You can get a small quantity from any laboratory. You please dip a small soft fresh cloth in this liquid and then using that cloth wipe the pen drive. Please see that the witness will not be very high. Take very little quantity. Definitely, the rust particles will go away.
The second chemical which can be used is Iso Propyl Alcohol. It is also very widely used in industry and a very good solvent for cleaning. This is a very common liquid available in even small laboratories. You can apply this solvent also as described in the other case. Another mild solvent which is not very effective is Acetone.
You can try any of the above three for cleaning the pen drive. But a word of caution, if it is must only you are advised to clean and use this pen drive.

A rusted pen drive can be cleaned with a hard cloth and then rubbing it with a damp cloth. Even use of a fine sandpaper can also be done but care should be taken that dust does not enter in the connecting side.

A pen drive has two parts - one which sits in the USB port while the other part which is the body and remains outside the gadget. So important point is where it is rusted. If it is the outer body part which remains outside the gadget when it is connected then there is nothing to be worried. If it is in the small part which sits in the USB port then a careful cleaning of rust is required otherwise it may damage the USB port in the gadget due to the abrasive effect of the rusty surface.

Generally, rust will be on the metallic outer body and the inner plastic and and electronic assemblies will not be affected.

Regarding virus and corrupt files if a pen drive have these problems then after connecting them to the laptop one has to run an antivirus program to clean this pen drive. Anyway this aspect is nothing to do with rusting.

Nowadays USB adapters are also available and pen drive can be fixed in that before connecting the adaptor to the laptop. It can be used as a dedicated adaptor. As you need not to remove the pen drive from the adaptor time to time, the question of damage will not be there.

So, in my opinion, there is absolutely no problem in using this pen drive.

It will be difficult to use a rusted pen drive again because it can make your computer harmful either through a virus or your programs may not work properly. If we use silicon spray on the metal part, and if we use a cloth to wipe on the metal part, sometimes the rust will disappear but the device will not work again. You will have to take new pen drive to work on your computer.

The open part of the rusted pen drive can easily be cleaned by dipping a clean piece of cloth in alcohols (for use in chemical labs) and then rubbing it. After rubbing and cleaning the part with alcohol, it should again be rubbed with another piece of cloth dipping it in clean water.

If the files in the pen drive are not corrupted by computer virus, the pen drive can be utilized. Whenever the particular pen drive is inserted into a computer or a laptop, a message will come if the files are corrupted by virus.

Most pen drives have the key component (storage board) that is encase in a plastic/fibre or a metal body. Often the rust happend at the point where we insert it into the computer and at the junction of the metal end and the encasing body where moisture or water can linger on and over a period of time form rust.

An unused pen drive does not increase the risk of a virus entry into the PC or Laptop. If the pen drive has already been corrupted then it would.

If you have any memorable data in it then the simplest thing is to use a little vinegar or warm water with baking soda. Wet the tip of a soft cloth and then wipe the rust away, simple soft brushes can also be used to scrape off. Once it is dry, then you can connect it to a spare USB cable, instead on plugging the old but important pen drive direclty. The USB cable takes the brunt of the mechanical damage.

Other way to get rid of rust is, first to gently clean the area with a home detergent solution on the tip of a soft cleaning cloth. After this, we can use isopropyl alcohol to clean and then dry it. If you are using the isopropyl alcohol, then it's wise to remember that it is inflammable. Rust removal aerosol sprays are available that you can use (Zorrick from Pidilite).

If the pen drive is not important, then you can dispose it off, why risk introducing rust/corrosion into the computer port.

If the pen drive has really important or valuable information, then I would say seek professional help instead of trying self help and risk losing the contents.