@beef1999; first of all, it might depend on the version of the proxy you are running. if your support contract ran out, i would assume you might be on an older version of the proxy which is actually easier to get back online. either way, for now, try starting it up from the windows services panel instead. If it is unable to start it may give you some more information. Also, check Event viewer after this if it does fail.
In case you must re-install - Note that the configuration file is stored in the install directory; again the exact location is dependent upon the version, i think the file structure changed a bit through the versions. I believe it is an .xml file (look for it in the install folders,' c:\program files\interactive intelligence\interaction sip proxy\resources' for example). look for 'configuration.xml' in the name of the file. you can open it up in notepad or IE and check to see if the settings are there. make a copy of that file and store it OUTSIDE of the install folders in the event you need to re-install. Once you re-install, put that file back into the default location, overwriting the new one, then restart the service from services panel. This will allow the proxy apply the new settings.