I have placed a high performance cd&dvd player laser lens cleaner in my Lg Dvd recorder model DR 275 but it comes up with a message ' unknown disc, please check disc again' or" No disc " Any DVD disc has the same result Please what can I do?

Most DVD player Unknown Disk / No disk errors are the result of 1 of 3 things. As you obviously suspected, a dirty laser lens is one. The wrong kind of disk is another (DVDRW often is not recognized). And the other is a dead or dying drive motor. Very rarely can the motor be fixed because it is usually an integral part of a larger assembly and is difficult to access and nearly impossible to replace as a single discreet component. I'm afraid you are likely going to have to replace the unit as it is probably not economically feasible to repair it. Sorry about the bad news but it is a very common failure. I know this isn't very helpful so feel free to repost the question for another user, maybe someone else will have better news. Good luck. Joe.