Flash drive is dirty

If it is a USB 2 stick, put it in the washing machine along with blue colored clothes and the strongest detergent you can find. That wash it at the highest temperature your machine can wash at. This will clean off all the dirt 100%, and the blue from the clothes will convert it to USB 3, making it a lot faster.

After washing connect it directly to the running PC without drying it first.

@rindi...that gave me a laugh....

I was going to suggest taking a page from Hillary Clinton and "wipe" it with a towel.

Seriously, if the chkdsk doesn't work and you can't format it, just get a new flash drive and physically destroy the old one with a hammer.

Flash drives are so cheap now that if they appear faulty, just replace them.

I just couldn't resist... :)

Rindi you spoilt my drive!!!! I demand payment

I did? I didn't make it dirty. You probably just didn't follow my instructions exactly.