Nokia asha 202 probs

why i cant access my chat & mail app.. when i open it . it says application not ready. or sometimes it says invalid application. what should i do... please help me.?

Hi Elmer_HD,
Thank you for your post and welcome to the forum.
Please perform a hard reset and update or reinstall the software on your phone. 
Connect your phone to Nokia Suite and make a back up via Tools > Back up. Make sure you don't tick the Settings box. Once you made the back up, disconnect the phone from your PC and enter *#7370# into your phone and default security code 12345, unless you've changed this code yourself. 
When the phone has rebooted, connect your phone with Nokia Suite again and click on the green arrow icon where a software update will be displayed. If no update is shown, please reinstall the current software. This option is displayed in blue. After the software has been installed, go to Tools > Restore to restore the back up. 
Please get back to me if this resolves the issue, otherwise I can provide further support.
If my post has helped you in any way, please accept it as a solution or click on the white star, so that other users will be able to benefit from it too.