My computer won't start up its saying check sinnal cable what do I do

Do you hear the fans or see a light when you press its button?

Yh the blue light comes on and u can hear the fans

Sounds like your monitor is not connected properly. Your computer is starting up.

Every looks connect I've pushed them all in it still not working

Try a different cable, and do you have a video card, or does the cable plug in on the main board? If it's a video card, you can re-seat the card.

What a vieods card and I've tried all the leads

A video card is the interface between your PC and the monitor. If you have access to another monitor I would use it to test if the problem is the monitor or the video card.

P.S. This is a message board not chat or test messaging. Please don't use text speak here.