If you take your time, don't get too heavy handed, it'll do at a push.The problem with the file is it's teeth are likely to dig into the wood if you're not careful. You could also take it out to the kerb and rub it on the corner of that, also gently or you might snap it completely.
Just go buy some sandpaper. It doesn't cost that much and all hardware stores have it, as well as walmart. You can get different grits from very coarse to very fine. If you want to get rid of paint, I would say to go with a medium grit and finish with a finer grit. If you are trying to get rid of dings and scratches, go with something a little coarser than medium. But always finish with a finer grit to get it smooth.
I agree with pedal demon find an outside surface that you can gently rub the part to be sanded on. However sandpaper doesn't cost a lot and you can use it again and again.
What can I use I can't find some sand board and I don't really want to go buy iti do have a file would that work?
