hi could anyone offer advice my headlights dont come on all the time unless i thump the glass , thought it may be loose connextion however even when on if i leave them on and switch off ignition then switch it on again i still have to bang glass . was offside for few weeks now it can be nearside as well any help guys ?

 

You don't say what model, or what type of bulb, (H4, H1 H7 etc)?

I'd check: connectors behind the bulb.
Earths.
The bulbs themselves, ESPECIALLY if they aren't H4's.

Look for signs of corrosion, loose connections, overheating etc.

Could also be a sticky relay.

Alcazar