Never heard of that or the wireless not working once you install the driver if it is missing once Windows 7 starts up the first time.
There are three different Wireless drivers posted for Windows 7 on the Lenovo Support Downloads webpage which is the place you'd normally get it: Drivers and software - Lenovo V570 Notebook
If you don't know what wireless device you have you can try all three, or trace the actual make/model using Hardware Identification.
In addition you can back up Windows/System32 folder to browse for any drivers after a reinstall - they are all there.
Once the correct driver installs, 95% of the time you'll see the wireless 5 bar icon appear in System Tray with a yellow light showing that networks are available to connect. You'd only need to select yours and give the wireless key. If that fails, rightclick the icon to Troubleshoot which may sort it for you.
If everything fails, power cycle your Modem, router and reboot PC.
Other steps for getting a perfect Clean Reinstall - Factory OEM Windows 7