Windows partition won't let me boot to my Linux partition

Title says it all.
Sorry to be brief on details, I have been meaning to post this for quite some time now before tekxit was a thing but I kept forgetting. Now that I remember it's late and I really, REALLY need to go to bed or I might never wake up for work tomorrow.

I partitioned my hard drive on my laptop. It was original booting Linux. I made a windows partition for Win10. Now I cannot boot into my Linux partition.

I'm a novice noob scumlord when it comes to partitioning and dual booting, so be gentle.

Is Linux listed in the GRUB menu? Or does the system not display GRUB and just boot straight into Windows. And how old is this PC and what Linux Distro did you install.

There's your problem. When you install windows 10 it will overwrite the bootloader. It's not going to use GRUB. To solve this issue you will have to repair and regenerate the grub config.

As for what to do, whatever distro you are using you're going to have to plug in the flash drive you used to install your distro and regenerate the grub config file.

Also word of advice Windows 10 will overwrite the bootloader with each big update...

I have that turned off, but good to know.

Win10 wasn't entirely my choice. I needed it for work.

I don't think I have linux installed on my old flash drive. I think I replaced that with my Win10 install. If I just re-replace that with an xUbuntu (that's the distro I use, btw) install, will it still generate the GRUB? Or does it need to be the exact install I used?

you're going to have to, you have no way to access your linux partition without it.

Make sure you make a separate efi partition for linux.