How do you fix USB port inside phone?

YouTube is usually your friend. There's a high probability that soldering is involved since most port defects require a swap.

For starters, what phone are we talking about here?

I'd say just go to Best Buy and swap it out. It's the best thing to do long term.

You can try to use a tiny jeweler's screwdriver to bend the connector back, but you risk breaking it off or weakening it so it breaks off later.

Otherwise you'd have to open it up and replace the part (buying new port, soldering, etc.).