Restoring TWRP Nandroid .win files

My Mum’s managed to mess up her tablet (seems to have reset it but not factory reset, as it’s still encrypted, password protected, etc, just all her apps and even Apex Launcher have vanished) and the only recent backup I can find is a TWRP backup made with Online Nandroid Backup.

TWRP doesn’t seem to recognise the files however, as it doesn’t list any backups. I looked at the log and see that when pointed to the internal storage (which it can’t mount as it’s encrypted), it looks in /data/media/TWRP/ and I’ve recreated that structure on the microSD (where the backups are), giving me /data/media/TWRP/BACKUPS/0000000000000000/2015-04-05–07-14-50/

In that folder I have:
boot.emmc.win
cache.ext4.win
data.ext4.win
recovery.emmc.win
system.ext4.win

and .md5 files for each of those.

The .win files I can open with 7-zip, to show the files without that extension (e.g. data.ext4).

If anyone could help me restore this backup I (and more importantly my Mum) would be very grateful!

I tried installing Nandroid Manager and ES File Explorer and both failed, so something’s clearly messed up. SU 2.46 is installed and I checked root with Root Checker and updated Busybox.