DSL connection

I have DSL service through AT&T. For about 2 weeks I had connection on and off, I would be connected for a few minutes and suddenly the connection would drop. The last 2 weeks no connection at all. Speaking with the AT&T "techs" gets me no where, they just want to send someone out and charge me!!! I checked the phone line by connecting a phone and the line works ok. I took the CPU to a friends house and connected the computer to his DSL with no problem,which tells me the Ethernet card is OK. I'm thinking there is something wrong with the modem, both the Internet and Activity lights don't light up. I tried re-setting the modem, still not working. Is there any way to "repair" a modem to avoid purchasing a new one? Any other suggestions of what could be wrong? THANKS!!!