Lost wireless signal on wireless router

[cableman]

I have an older ativa router don't know the model number right off but it has worked fine and I have 4 hardwired computers wired in and on occasion i use my netbook for a wireless connection. I haven't used it in a few weeks and now it won't work. nothing has been changed on any computer. I can sometimes get a connection but it show packages sent but none received and wont work. do you think the wireless part of the router went bad and how do I know how to check. Please help need the wireless service for my netbook and my new laptop which would not pick up the signal either and i have no password or restrictions on it . They normally just pick it up and work. Please help if you know what i need to do.