Unsure if this is the right section, but...
A user and I did a deal in August, late August. Deal was smooth and all, but after a long time, the user charged back the $300 he sent me and my paypal is now at -$300 balance. I don't have a bank account linked or anything so what happens if I just leave it? It's been -$300 for 29+ days.
Nothing will happen, just stop using the paypal account. Something similar happened to me awhile ago, and 2 years later nothing has happened. DOn't worry about it.