my data in my vehicle not working

yeah bro this issue happen sometimes

maybe first check if your OnStar subscription still active or expired, because if it end then in-vehicle data stop working

also try simple things like:

restart your car system (turn off car for few mins then start again)
check signal/network in your area
go in vehicle settings and see if data is enabled
if still not working then better contact OnStar support, sometimes they need to refresh connection from their side

hope it help