I updated my voicemail and with out thinking I allowed apps that are not from google play to access my phones features causing some things to disappear, on my phone How do i change my settings back to where only things from the play store and so on can be installed?
This may vary by OS version or modifications your manufacturer may have made, but the setting you're looking for is:
Settings | Security | Unknown sources
You'll want that to be unchecked to prevent apps from being installed from unofficial sources (read: the Google Play Store).
(If that's not what you're looking for, please edit your question to make it more clear what you're asking.)