Wireless connection

Hello,
I have a dell studio that is less than a year old. I'm not too savy with computers snd could use some help!!
We have a wireless set up in a building in our backyard. It's been just fine most of the time, but for the last few weeks it has become almost impossible to get on line. We moved the motem, but each time I want to get on line I have to go and turn the motem off and then back on. Then, MAYBE I can get on line, depending on my location. I used to get on any where in the house. Do you think it is my computer, or a motem problem? Why was I able to get on just weeks ago and now it's an issue? My husband can get on without a problem, but he usually is sitting somewhere different. HELP PLEASE!!! Thanks, Scout