How do I re-register a computer if ive deleted it by mistake :-)

You just restart the service on the computer you wish to re-add it to your list. It will show up in no time.

Ive tried restarting it and reinstalling pc monitor but my computer still wont appear.

Are you sure you restarted the PC Monitor service?

If you reinstalled the application, did you run it, configure your credentials, pressed the validate account button, then you pressed the start service?

Please confirm.

Ive tried all the above and my pc is now showing, but it is offline and on my phone the only command showing is wake up ?

Make sure that the service is online and he has access to the internet on port 443. Try this command on windows xp command prompt:

telnet ws18.pulseway.com 443

If you see a blank window with a blinking cursor then everything works on your side, however if you get a Connection Timeout error your firewall / network administrator is blocking traffic.