Can I still file taxes if my employer made a mistake?

You may want to wait for a corrected W-2. If you try to guestimate how much you actually earned, you will be forced to redo your taxes with an addendum form. You may also want to ask your former Human Resources person to print you off a corrected W-2 form. They should have the software to do so. Also, another way you may be able to print it off yourself is by looking for a website that is usually on some checks, so you may get information on your wages, W-2 etc. I hope this helps.