Okay so here is the thing. First I want to let you know that I know absolutely nothing about Linux.
So I installed Ubuntu along with my windows 8. When restarted the computer, windows 8 was booted without anyone asking me what OS I wanted, so googling it made me download EasyBCD, which mess with the Bios or something. So downloaded it, added an entry for Ubuntu, restarted, and Windows Boot asked me what OS I want, and everything worked fine, until I messed things up. I booted Windows 8, went to EasyBCD, made Ubuntu the default OS, and checked "Skip the Boot Menu". Now every time I start my PC, Ubuntu is started. Pretty good. Now the thing is, how can I start my windows 8 if I ever want to? Googling for like an hour made me install Grub Customizer, messed a little with it, and now when I start my PC, a Grub shows up with a list of the OS I have, repair mode for Ubuntu, and memory test. Now if I select Windows 8, the screen turns black with two white sentences at the top for less than half a second, then another black screen with around 3,4 sentences which goes to fast I can't read, and then it go back to GRUB list as if nothing happened. Ubuntu boots fine, I just can't start Windows 8. Oh yeah I also disabled Secure Boot, since googling told me that would work, but it didn't. So yeah, if anyone can help me, it would be much appreciated.