วิธี reset account/gmail on android phone as following
1. Go to Settings
2. Select Application Manager -> ALL (swipe to the right to select ALL) Select Google Play Store Select Force Stop and Clear data.
3. Go back to ALL and select Google Services Framework. >> Select Clear data.
4. Go to Settings->Accounts->Google.
5. Remove your Google/Gmail account.
6. Shutdown your phone and turn it back on.
7 Go to Play Store. Enter your Google/Gmail account. See if you can use it to download apps.