Question Problem with my dimm slot on a laptop

[Suppreskey]

My laptop is a ideapad 300 it came with 6 gigs of ram that I changed for 1 8gb ram stick because it was blue screening to much then it didn't stop went to an expert and he changed the ram stick to the other dimm slot, but when he did that he didn't tell me but it worked fine, but then I stupidly changed it back and it started crashing again, when I put the ram stick back to the place the expert placed it in it doesn't boot, someone help

 

[rgd1101]

You probably did something wrong, take it back to the expert.