In the rarest moment if you lost the track of your progress Level in Pokémon Go, here is how to fix it.
Some people using Pokémon Go with Google accounts are facing issues linked with Pokémon Go app. The possible solution to restore the progress is logging out of the app and then again logging in.
If it does not help, try to clear app cache and reinstalling it to get back your Level.
The third and the last resort will be logging out of your Google Account and then log in. This might bother you a bit but take as last option to getting back your progress to Level 1.
If things do not work out, you have to send a bug report to Niantic.