Why won't my RAM slots recognize my RAM?

Do the old, previously, used RAM sticks still work? If so you either have a bad new RAM stick(s) or you have passed the maximum amount of RAM allowed by your motherboard. Try checking the documentation on Lenovo's support website or your owner's manual to see what the maximum amount of RAM is supported in GB.

Yes they both still work on my friends pc and the max ram capacity is 20gbs but with the 4gb already integrated I only purchased 8gb sticks for my ram upgrade. When I first brought the 2nd one it did do its job and increased my ram but like 3 weeks later my screen suddenly frozed and blue screened and when it restarted it was back to the default 4gbs and after reseating constantly sometime it would work but after like a restart or battery dying, it instantly returns to the default 4gbs after restart

So just to make sure I have this right: There are two RAM slots on your computer? If you go into the BIOS could you tell us what it reads as the total Installed Memory? Also it probably wouldn't hurt to shoot the inside of the slot with some compressed air if you have some, although I doubt this will solve the problem. I wondering at this point if you either have a "unsupported" clock speed on the RAM or if they're just lemons. I would definitely try Brayden S' suggestion. If you are running Windows 10 you can create a bootable installer drive and run the windows memory test from the "repair this computer" menu.

I had the same problem I think its either the slot or the power is not supplied to the ram. My problem occurs after i put the laptop on bed during heavy task which heats up the laptop and after that it sometimes detect and most of the times not detected by the mother board