I have rooted my LYK-4503 from kingroot and then I uninstall the app and now I am not able to open google play store and I am not able to download or update any app... Please help me
Instead of Restoring the Stock rom, Just download the Latest version of the Play Store from the web and then move it to the System/app folder. Also, I recommend you don't use KingRoot. Instead, get a custom recovery and Flash SuperSu.
Kingroot really is a pain to work with. Only use it if nothing else works.
To fix your problem you should find the suitable version of gapps at opengapps.org. Make sure to select the correct architecture and android version and use a Gapps package
micro or higher.
Once you download the zip, copy it to your phone and install it with a recovery.