Issues with dual-booting after

[Lya_re]

I've been dual-booting Windows 8.1 and Linux Mint 17.3 for three years now without issue, until a few days ago when the laptop stopped going into bios and instead just says "reboot and select proper boot device".

I was using UEFI boot and switching to CSM boot recovered linux. From that I converted the Mint install back to UEFI but Windows remains elusive.

The current state:
Mint runs fine on UEFI boot but has a chance of freezing on splash. It used to do this occasionally too so I think it may not be relevant?
Can't find Windows anywhere. os-prober only shows Linux. Same with grub and everything else. boot-repair also doesn't list Windows.

Well, I fiddled a bunch with boot-repair, which among other things, asked me to create a new partition with the bios_grub flag. Not sure if it's relevant, but I thought it was weird since I never had issues with it before.

After lots of fiddling the most recent pastebin is below.
http://paste.ubuntu.com/p/rM5RwqSvGK/
... I'm pretty sure sda2 shouldn't look like that, should it?

[asinoro]

It worked also for Lenovo.
https://askubuntu.com/questions/984043/ ... 771#989771