L322 Fuel filter or faulty pump?

Hi All,
2003 4.4 broke down a few weeks ago. Garage manged to get it to start by tapping the fuel filter.
i therefore changed fuel filter this morning.

Unfortunately it refuses to start.

likely to be a knackered fuel pump or air in the fuel sytem?

Not sure what next move is. Thank you

Check for fuel pressure at the fuel rail while cranking.....if pressure pump OK, if no pressure pump fubar'd

Thank you, will do a google on how to do that.