Phone wont charge, and it used to be really hard to charge?

Hey, I have a samsung galaxy S. I've had it about 2 years and before that it was someones elses for maybe a year or two.

Anyway, about a year ago it was quite hard to charge and I had to sometimes put it on a certain angle for it to charge but eventually that went away after a month and started charging normally again.

But recently its been really difficult to charge and now it wont charge at all! I've tried scraping the usb port for lint and I've tried taking out the battery and I use all sorts of different chargers so that isn't the problem (unless its because I'm using off-brand chargers?)

I have dropped my phone quite a lot too so that could be the problem but I'm not sure..

I'd like to be able to fix it without going to a repair shop but I will if its necessary

Thanks! :)