Hello,
I recently installed Ubuntu along side my windows 10. Once I completed my Ubuntu setup I noticed that my Windows boot manager was gone. I though of repairing windows through my USB stick which had windows flashed in it and found that my Bios admin password is not accepting Special characters anymore, my password has a "+" in it. I am currently only able to access ubuntu, I tried removing CMOS battery for one hour but it didn't fix it, even tried alt + r but it doesn't work. If anyone knows how to fix this please let me know.