have you tried a hard reset on your router? there should be a little button on the rear just press and hold it for 30 seconds release and then power cycle the lot. Turn off pc turn off modem turn off router. Turn on modem allow to settle turn on router allow to settle turn on pc. Is the router connected via ethernet to the pc? if so browse the routers set up pages and set up your wireless and security again
if you lost your docs to get into the router simply press start and run type cmd a box will open type at the promt ipconfig /all
Type the default gateway address into you browser and your pages will come up. User name and password will be a combo of any of these words for user name user,root,admin or blank and the password will be user,root,admin password or blank hope this helps