You're unable to get to your computer because you're behind a NAT'ing system of some sort. In other words, your computer is on a private, internal network and being NAT'd via the building's NAT device, under their control so there is no easy way to get back in, in this sense.
One way would be to create a reverse SSH tunnel initiated from your workstation, outbound over the Internet, destined to an ssh daemon that you can connect to from home.
Once this is established, then you can ssh to localhost that you set up the reverse tunnel on (which would be redirected, via the reverse tunnel) to your system, from the ssh host that you connected to, via the reverse tunnel.
Hope this helps?
Afterwards, you may want to look into writing a small script for a cronjob to keep this connection alive, reconnect on disconnect, etc. and use ssh-agent properly, for passwordless connections - if set up properly, the passphrase would only need to be set once (if that).