I need windows 7 drivers for a lenovo ideapad 320-15iap?

They may not be available. Ask lenovo / lenovo website.

Try the first page of listings here

Your best resolution is to install windows 10 again. It does not crash due to updates because it is monitored constantly for errors and problems. It has a built in recovery program. Any update can be removed. Also, it has a reset program that re-installs windows 10. It also has a repair program.
You simply had a bad update or temporary glitch that has since been fixed.
If your unit was developed for windows 10, then no other drivers were ever written for it. They launched the laptop starting with windows 10 so there was no need for windows 7 drivers to be researched and developed.
However, Windows 10 is a good, clean operating system. Some folks like to simplify the system by deactivating most of the features that cause it to be complicated. My Windows 10 now looks and acts like windows 7 but has lots of available features such as the programs in "updates and security" in settings.

You can either go to the Lenovo IdeaPad website and download the drivers from there or you can download i o bits driver booster install it run it let it install all of the drivers and then uninstall the thing it is adware but it does a great job automatically installing all of the needed drivers

They are the same drivers. Alternatively look for VISTA drivers.