I uninstalled this app by mistake and now when I am installing it back with the same password and email, it's not showing any of my older pics. Is there any way through which I can get those pictures back?
There is an official guide for the application to restore your pictures. Practically, you will have to connect the device to PC to copy the hidden directory to some other place.
For more information, access the FAQ page and scroll down to the last procedure. Your pictures are still there, only they're hidden and have another extension.
FAQ page: http://support.getkeepsafe.com/hc/en-us/articles/203189610-My-phone-is-damaged-how-to-restore-with-computer-