Since you're not at home, troubleshooting options (and the actions that you can take) are far more limited.
But you're not totally helpless. Here are some steps you can take to help narrow down the issue. If the problem ends up being with the Slingbox or your home network, there is not much you can do unless a knowledgeable person is at home to help. But at least after trying some of these steps, you can narrow down the problem.
Verify your local Internet connection.
If you are looking at this web page, you have already done this. Without an Internet connection, you can't read this page ... or connect to your Slingbox.
If you are connected to the Internet, move on to step 2.
Does Internet viewing work anywhere else outside of home?
Have you ever connected to your Slingbox away from home before?
If you have never connected to your Slingbox away from home before, or if you've tried but it hasn't worked, then you'll need to configure your home network router properly for Internet viewing. Unfortunately, you'll need to wait until you get home to fix this, unless you can enlist someone at home to help.
If you have connected to your Slingbox away from home before, but it's not working now, have you made any recent changes to your home network router settings? If so, then those changes might be the problem. Unfortunately you'll need to wait until you get home to fix this, unless there is a knowledgeable person back there who can help.
If you haven't made any recent changes to your home network router, go to the next step.
It might be firewall settings.
Have you ever connected to your Slingbox on this computer before? Is this a computer that is administered by your employer?
If so, it may be the firewall on your computer that is not allowing the connection to your Slingbox. You might want to try connecting to your Slingbox from a different computer, or (if you have it) from SlingPlayer with your smartphone or tablet and a 3G/4G connection. (A Wi-Fi connection and your smartphone or tablet may have the same issue.)
Is it the local network?
Many networks in hotels and office buildings have limitations on the types of files that can be viewed (like streaming video). Try going somewhere else. If you are in a hotel or at work, try taking your portable computer out to a local Internet cafe and connecting from there.
If it works, the issue is the network. You may want to talk to the system administrator at your location to see if they can help you solve the problem.
It may be something at home.
Lastly, it might be something at home. Maybe the Slingbox itself got turned off or is unresponsive. Maybe your home network is down.
If you have made any changes to your network (like purchased a new router) since you hooked up your Slingbox, that may be the problem. If someone is at home, you should ask them to restart the Slingbox (and maybe your router as well) and see if that gets it back online. To restart it, just unplug the Slingbox from the wall outlet for about 10 seconds, then plug it back in.