Got a 95 Ford f150, it ran out of gas, put gas in it and now won't start. Fuel pump is working. Any idea why?

Try changing the fuel filter, try priming the pump by turning on the key for 3 sec. letting it sit a bit and do it repeatedly like 3 times, then try to start. If it don't start fuel pump may have burned up. Verify by checking the fuel pressure.

Pressure should be 35 to 45 lbs. using a gauge.

Fuel pump is working fine. How do you check the fuel pressure

How would you know that the fuel pump is ok without checking the pressure? Common to go bad after running out of fuel. Check by getting a fuel pressure gauge to be able to attach where the fuel filter is, check by doing a dead head check, fuel stopping at the pressure gauge, not running threw it, pressure should read and hold 45 lbs. minimum. You may be able to rent one from the local parts store, they require a deposit of the cost of the tool that you get back if you decide to return it.