Windows wont boot after psu change

Faithkid

Honorable
Aug 12, 2013
28
0
10,530
Hello. Need a little help. My pc was working fine but until i changed it into a new case and added a new psu . It turns on and everything but it says no operating system have been found but all the hard drives are connected and the windows 10 is in my m.2 ssd drive
When i check bois it shows everything is connected. Any ideas ?
And when i try and install a new windows it even shows my m.2 ssd drive being full. But any ideas how to make it work ? thanks.