Can't use wireless anymore

[spinachmuffin]

Hello, I had been enjoying using a wireless connection for months until it suddenly stopped working. It still "connects" but then says "Eingeschränketer zugriff" - restricted access (sorry, had to buy my laptop in germany) and I cannot use internet. I can still use internet if I connect the laptop with a cable to the router. Otherwise I have been relying on my kind neighbour who lets me use their wireless. There were a few days that I could mysteriously use my wireless again, but then it was gone again. It's been more than a month now. Could someone please help us? Thank you very much.

The laptop is from Acer and the OS is windows 7

 

[scout_03]

see your neighbourg