WINDOWS UPDATE JUST FUCKED MY LINUX PARTITION!!! Apparently, this is a common thing? I lost a whole bunch of stuff that I really wanted to keep :/

You could try to recover the lost data. If you want to, then you should immediately stop to use that hard drive.

Get another PC, an SATA to USB 3 adapter and try software like Recuva. Maybe you can rescue a good amount of your data.

But yeah, you shouldn't keep Windows and Linux on the same hdd.

Did it fuck up the partition or just the bootloader?
Windows really likes overwriting the bootloader so only Windows boots every time, in that case you can easily fix that though.

Oh, and do backups, especially when dual-booting. Windows does some crazy shit now and then.

@Makenshi too late, already reinstalled Linux :/

@deadlyRants partition table, I used to have an automated backup to my 4tb drive but I forgot to set it up since I switched to arch.

@Torbuntu I need windows for games. Which sucks.

@Nanos Most modern MB provides easy way to access boot menu i.e. F12

@Dacexi Yeah, Windows is a bitch when it comes to Dual Boot.

The best I have found to keep dual boot is to always access OSs using boot menu rather than depending on Grub for everything. Also, keep a boot repair USB for situations like this. It could be as easy as just booting to the USB and clicking repair.

Also, keep your partitions separate for /home. In that way, you can preserve a lot of settings and file in case you OS is completely fucked,

I don't think it should have done anything to your Linux partition. At best, it might have replaced the GRUB with the windows bootloader. Just use boot-repair and grub-customizer to bring it back.

@vergil I tried but it completely rewrote my partition table and I've already reinstalled Linux so I can't recover the data.