Why is my 2010 MacBook Pro not detecting RAM?
Verify that all the RAM you're trying is actually good, by installing each the SODIMMs in another machine. If the RAM is recognized, then it's OK.

If the RAM is good, then the memory modules are not being electrically connected to the motherboard in the Macbook (either because of a RAM socket problem, or a bad electrical connection(s) between the socket and the board), or there might be a failure within the electronics on the board.

If the RAM is good, the repair sounds like something that'd require professional attention. The Macbook may be considered "Vintage" or "Obsolete" by Apple; more information is on Apple's page here. If the machine is Vintage or Obsolete, Apple may decline to repair it and may further decline to provide replacement parts. 

However, you may be able to find a non-Apple service provider who can examine and perhaps repair the fault(s), as repair may require no parts, or parts which can be sourced other than from Apple.