I agree with mbreuer it's probably your Firewall on your work PC that isn't allowing incoming connections (they normally by default allow all outgoing connections).
The way to check is get someone from home to start the VPN and turn off your work PC firewall (as you have no IT Manager that should be possible) and see if they can see the work PC. If this works then unfortunately you don't have an IT Manager who can configure it for you! Also another way to check is to use another work PC and see if it can connect to your work PC.