Most issues can be solved by taking the following steps:
UPDATE
Open Google Play on your device, find Recolor and tap Update. If the button says 'Open' instead of 'Update', you already have the latest version.
RESTART
You can restart your device by pressing down your power button and holding it down until your Power Options appears on the screen. Tap Restart.
CHECK RECOLOR
After the steps above, open your Recolor app and see if the issue still persists.
SOLUTIONS
Check the articles under Solutions menu to see if there already is a quick fix for the issue you are experiencing.