Steam proble, the application not start

Hello there, I had buy thee steam subscription, ot was working well but today It stops working showing this message

I have 2 computers but the other one is off (its a laptop), I even turned on the laptop to see if there it works and it works! but I Need to run it on my desktop pc for performance.

I was using it on my desktop pc without a problem until today a few hours ago when that problem has happened.

PD: My desktop PC have internet access andjust to try I opened an played an online game, the network is ok. My steam user is gustavotero7 if thtat helps

How i can solve it? I need to finish a project soon