I have a garmin 5212 and I have lines through it and no pic

All you can do is send in to Garmin for repair. Call them for pricing.

Any problems with the picture/graphics is usually attributed to a bad LCD display. Maybe the back light went out.

Have you tried using the settings option and turning up or down the brightness?

Need to login to. The phone system and change it back.

Try unplugging the phone line on the base of the phone and replugging it.

It sounds like your phone is in do-not-disturb. Press the blue key. Press the no (# key) until you see DND, then press Yes (* key). Press Turn off (0 key).

Contact your system admin or vendor. The time is set in the phone system, not in the phone.

If there is a problem with the connection, or low bandwidth, you can change the protocol to just use G 7.29 to improve performance. That is if the PBX supports it.

instructions http://www.tc.mtu.edu/voice/voiceservices/voip/5212/5212-5224userguide.pdf

No you cannot.
The Mitel 5212 uses propitiatory software unlike SKYPE which uses open architecture software. You IS Dept. could invest into a Teleworker Server and you could have all of the features of your office phone at home.