Wireless internet doesn't work but wired does?

For about 4/5 years my wireless has been working perfectly no problems or anything. Now this happened about 2 months ago. My computer says its connected but when i type google in the browser and search, it says the internet is not connected? The modem is hooked up in my brothers room and the Linksys router is hooked up fine. Do i need to replace the router? Help please? By the way, i disconnect the internet wait 30 seconds and put the router back in, it only works for about 30/40 minutes then it doesn't work again.