How can I fix my Audi 80 if the engine won't start?

I've tried jumping the battery and replacing the spark plugs, but the engine still won't turn over. I suspect it may be an issue with the fuel filter or fuel pump. Any suggestions on how to fix this issue?

Check the fuel pressure and make sure it matches the manufacturer's specifications. If it's lower than it should be, try replacing your fuel filter first before investing in a new fuel pump.

Have you checked the ignition system? It's possible that a faulty ignition coil or distributor could be preventing the engine from starting. You should also check your fuses and relays for any signs of damage.