Hard drive only works sometimes?

Hello everyone,

I installed a new M.2 SSD this morning, and since then, both of my external hard drives haven't worked. I then removed the new one, but the other two still didn't work. I then changed the SATA connection for the hard drives, but my system still didn't recognize them. After a while, it finally worked. When I restarted the PC, they weren't recognized again, even though I hadn't changed anything. Does anyone have any idea why this is?