I accidentally installed linux on the windows partition
Do you mean this (failed) installation of Garuda or another one?
I don’t have USB and I don’t really know what to do now
If you mean for booting the .iso without having a usb media at hand, if understand correctly you have GRUB installed, try this: Handy scripts you'd like to share - #44 by meanruse
What is this error about?
I am not sure, I think the boot disk fails to find its compressed filesystem.
It sounds like you used a similar method to install
I don’t have a pendrive and I installed linux using dualboot on a separate partition via grub and multiboot usb creator
I don’t know “multiboot usb creator” but I vaguely recall having had some similar error when I first tried booting from .iso file the wrong way.