Wireless Router

I am so frustrated....I can't get my wireless router to work. We used it before and then we switched to dsl and stopped needing it. Now, we have switched back and I can't get it hooked up for nothing! So, I called tech. support and they couldn't even help me. They were frustrating me because everything I told them I did, they kept telling me to do again. I called twice and still do not have it working!