Try reinstalling the wireless driver
in Device Manager, by uninstalling it and then rebooting which will reinstall it automatically.
Next try updating the wireless driver. Uninstall the wireless driver in Control Panel>Programs and Features. Plug in by ethernet cable and connect to the web. Run all IMportant and Optional Windows Updates after enabling Automatically get recommended drivers and updates for your hardware (Step 3).
If after several reboots the driver isn't provided, import it from the PC maker's Support Downloads webpage. Driver Install - Device Manager
If that fails and this is the corrupt factory preinstalled Windows 7 with all of the bloatware which smothers Windows 7, consider getting a superior Clean Reinstall - Factory OEM Windows 7