"trying" to assist? Gee, thanks.
It sounds like you are missing a bunch of apps on your BB, including phone. You should have more than Core applications and System software. Fortunatly, it sounds as if you don't have an IT policy. (even if there was it wouldn't show what the policy is or what it prohibits or requires, just if there was one loaded on the phone.)
I recommend updating your software to the latest version and adding back what is missing during that process.
You're going to need to install the Desktop Manager Software on to your PC. Make sure the BB is not plugged in while installing the software. Get Desktop Manager here: Desktop Manager 4.2
Then download and intall the latest software for the 7100/7105 to your PC.
I think the latest version for the 7100 is from Bharti right now. Get it here: Latest OS's for BB's
After both of these files are downloaded AND installed on your PC, delete the file "vendor.xml" (only the vendor.xml, nothing else) file located in c:\program files\common files\research in motion\apploader.
Then plug in the BB, and run Desktop Manager. It should prompt you to update.
Make sure you check the boxes for everything you want installed on the BB, including "Phone."