Inability to download app/games
1. Please do note that the 16GB is your internal memory size and does not always refer to free/available space (kindly ensure that "free space" also reads 16GB).
2. If you do have several Gigabyte of free space and still cannot download app/games, then the system may be corrupt requiring a hard reset - I am takingr it for granted that you download you app from Google Play Store (which is always the best)
3. With a working SD card installed, you can use an app calle ATSTRO File Manager to move media files like photos, music and videos from the internal memory to it (SD card)
Inability to read the SD Card
1. Please do note that your device comes with 1 year warranty - meaning that you can get a free replacement/fix if the SD/Memory card slot has failed (which is one of the possible causes of the divice's inability to read the card"
2. Please do try a different SD card to be sure that it is not the SD card that is faulty.
3. Also try and format the original SD card to be sure that it is not just having bad sectors or corrupted.
4. Also note that the device will not read an SD card that is password protected.
Please kindly comment below for any necessary further assistance on this.