Hello!
Are other apps functioning correctly?
If so, lets try the following to help clear up your Play Store issue.
1. Open your device's Settings app
2. Scroll down and tap Apps or Application manager
3. Find the Google Play Store and tap on it
4. Tap force stop
5. Tap clear cache (if this option isn't showing tap storage on google play store to see it)
Try reopening the play store. If this does not work, you can also attempt the above 5 steps with Google Play Services which should be right above Google Play Store in that application settings section.