user manual for pro slide mitre saw?

I suspect you actually have a Performance Power (B&Q) saw - it has PRO written on the dust bag. I used to have one.

I suspect that you've accidentally switched the laser light off when you were moving it about - I used to do this all the time - there's a yellow push switch - just press it.

Let there be light...
December 2015

Unlikely you will. It is probably a cheap Chinese generioc product badged up with a store own brand label and enjoying minimal, if any, support.

XXX
December 2015