[Q] Unable to update apps topic

The device that i use is a Oneplus one 64gb edition
Android Version 4.4.4
Google Play store version : 4.9.13

Since 8th jan 2015 , i am unable to update or install new apps. The initial error message i got was Error 905. I checked the internet and followed the below steps to resolve it
1) Go to Settings
2) Apps -> all apps
3) find google play store - > uninstall any updates -> clear cache and data
4) Reboot the phone
5) launch google play store , wait till it updates itself and try to download the apps again.

Inspite of following these steps , i was still getting the error message.
I have hard reset the phone 5 times in the last 4 days but to no avail.

Since the last 2 days i am getting error 495.
I have removed my google account from my phone accounts and added it back ( this is as per the number of blogs that are floating on the internet ) but to no avail.

Play store selectively updates apps.

I thought it could be a problem with my WiFi network . So i tried updating/downloading apps using my Cellular network but the problem persists.

Could you please help me out with this issue as my phone currently is not a SMARTphone like it is supposed to be.

I have been flashing roms for the last 2 months on my oneplus one i.e moving between Kitkat roms and Lollipop roms . could this be the problem for my play store to play up ? ( out of the box question)