[karebo]

Phone Model: Alps Karbonn A2+, running 4.2.2. Jelly Bean with an 8GB SD-card installed.

Problem: A few days ago, 'Whatsapp Messenger' disappeared completely from my phone. There is no icon, and its not in the Apps Manager window. There were files from the app left over in my sd card, though (Whatsapp Profile Pics, Media and other folders).
The Play Store lists it as installed, and though I've tried using a Chrome extension to download it and tried to reinstall it, the app doesn't install.

This has occurred once before, with MoonReader Pro when I assumed the subscription period was over or it was a problem with the app, and consequently switched to another app. As it is Whatsapp is somewhat indispensable in that its the commonest messenger among my friends and classmates, and our Uni batch has a group on it where frequent updates about classes and stuff are posted. Note that these two apps disappeared with almost a month between them and no other app has given me any trouble before, during or after.

Device Situation: I have around 100 mb of internal memory and almost 1GB of SD-card memory free, and have been running Whatsapp for almost a year now with no problems whatsoever. All virus checks (done with Avast Pro) came out clean over a period of one week.

Possible Cause: For some time before that, I'd been switching between two SD-cards, one which didn't have Whatsapp (or any other app) installed that I use to store movies and stuff and the other that has all the apps installed in it and stores my music and shorter videos. I don't know if that's the cause, but its the only thing other than a virus that I can think of. I'm not tech savvy at all

What I've Tried: 1) Rebooting the cell, removing the battery and putting it in again before rebooting the cell.
2) Logging out of my Google account on cell, logging in with another and trying to reinstall Whatsapp.

I've tried to find solutions on the web but can't seem to find any. If anyone could shed some light on this, I'd be very grateful.

[B. Diddy]

Welcome to Android Central! First of all, thanks so much for describing your issue in such organized detail. It makes it so much easier for us!

It may be what you were suspecting--swapping the SD cards might break an app, if that app was relying on the SD card to store some data. Try inserting the SD card that had WhatsApp partially installed on it. Then go to the WhatsApp page on Google Play, and see if you can select Uninstall. If it successfully uninstalls, then use a file manager and erase any WhatsApp related folders on the SD card. Now try to install it again.