It depends on whether you can get at the laser. That may involve taking the lid off as the laser often is buried deep inside.
So if you feel confident attacking it with a screwdriver you could pop the lid off and wipe the laser with a cotton bud lightly socked in Isopropyl Alcohol (can get it from Maplin). Unplug from the mains and wait at least 10 minutes for the power supply to discharge completely first though!
If it is gunk on the laser then that may do the trick. If you don't fancy the idea then you can get cleaning disks which have a little brush that cleans the laser. Never used one so can't comment on how effective they are. But I have used the lid off and cotton bud method (but then i am a highly trained professional audio equipment bodger

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However lasers can and do fail, depending on how much use you have had from it. And they can be expensive to replace. Especially if you are paying someone else to do the job.