How do I fix "App already installed/app not compatible" error in Google Play?

[Caitlin s1]

I recently updated my phone to andriod 6.0 marshmallow to the 6.1 version, my apps on my SD card were wiped clean and I found google play store wasnt opening, after resetting my phone I found it was opening, but the store wasn't letting my apps downloading again and saying they were "already installed", I tried to download a 700kb app to see if it was working and it began to say "insufficent storage" for any app, I have an empty SD card and a GB of storage left , I went through and disabled the store, re installed it and cleared the cache and everything. Now it is saying that the device isn't compatable and in grey saying it's already installed, I managed to get one app to download but it does stop half way through to tell me that I don't have enough storage.
Help??

 

[B. Diddy]

Welcome to Android Central! Which phone? Was this an official system update pushed over-the-air, or did you manually download the update from a website and install it yourself? Were the apps on your SD moved there using the Move to SD command in Settings>Apps, or had you formatted the card to be used as Internal (Adoptable) Storage?

 

[Caitlin s1]

Im using a cheap phone (Vodafone smart mini 7) Yes I did get the update from andriod itself in the "About phone" Area in settings. My apps were all placed onto the sd and the default write disk was the SD card, I moved them myself

 

[B. Diddy]

Is the phone running Marshmallow? Check in Settings>About Phone>Android Version Number. If so, did you format the SD card to be Internal (Adoptable) Storage or Portable Storage?

 

[Caitlin s1]

Yes it is running marshmallow, and it has been formatted as internal storage, I can still save photos, files, songs ect

 

[Caitlin s1]

The update did stop when it started to load, so I had to turn my phone back on, which i'm wondering if it's triggered a glitch?

 

[B. Diddy]

It's hard to say exactly what went wrong, but it probably has to do with the fact that your SD card was formatted as Internal Storage. If something related to the card glitched, then any app that was installed to the card might not be accessible, even though the system still thinks it's installed. You might need to start from scratch with a new card.

 

[Caitlin s1]

I did insert a new card, still having the same error, what I thought was inserting the card into another phone, downloading everything there and then putting it onto my phone (by using portable storage) I don't know if it'd work but I might try, thank you Do you think it'd work?