comp won’t post

I was adding a cd-rw to my comp. When I put it in my comp. won’t post. I have reseated all my cables and,ram and cards. The comp. was working fine until then. I get power to my keyboard and my optical mouse but it never sends power to the monitor. Ihave also checked to see if something is shorting the motherboard but didn’t find anything there. Any help would be appreciated.
David