Its just a lamp holder plane and simple, pretty common fault on lights is the lamp holders go or the wire connection to them.
Could try an electrical wholesaler, but they will probably just flog you some new fittings.
Pics of the fitting would help and where the lamp holder used to fit into it, see what can be jerry rigged etc
If you have the circular ones with frosted glass fronts? the middle often pops out and can be replaced keeping the surround, say if you have those polished steel
triangular surrounds, just colour match and replace the centers, check if its gonna fit first tho, they can be tight.
Ps. Im mostly using
t5 link lights now for undercupboard / counter lights, bulb last forever and very easy to fit.
pps. You could probably just redo the contacts on that lamp holder but couldn't guarantee a good result which might overheat and burn out so probably best not to do that
