I have a LG LHB335 BLU-RAY HOME THEATER SYSTEM which is not 3D Now I bought a 3D TV So I want to buy 3D blu ray player My question is Can I buy any 3D blu ray player and use my lg oldsound system?

It is very likely that an existing theater sound system will work with any new Bluray player without an issue. However, there is a huge range of equipment and an even larger number of combinations of player and sound system, so it cannot be guaranteed. There are likely to be a few combinations that will prove problematic.

An older sound system may be designed to handle 5.1 speaker configurations or even 3.1 configurations. It is likely that the new payer will be delivering 7.1 sound. In almost all cases, a 5.1 or 3.1 sound system will work although without the benefit of the additional channels.

For a definitive answer, it is worth discussing specific model numbers with the store salesman and ensuring a refund option if the advice from the salesman is incorrect.