I dual booted through usb after installation the computer restarted and ended up at busy box. I gave up waiting for root file system. and some other lines and in the end Alert /device/sda7 does not exist. Dropping to shell and if I try to boot Windows it's showing Windows needs repair. Both are installed on one hard drive. So basically I can't access any OS right now. Plz help
Put the Ubuntu OS in a flash drive (not SD card-it doesn't work!). Put the flash drive into your PC. After that start it. When your computer logo appears (not OS logo) , press F12 several times. You will see a black menu with several elections. Press enter on that with the name of your flash drive (on which you installed OS). You will see "try Ubuntu without installing" and "install Ubuntu" . Press enter on "try Ubuntu without installing" . Install Ubuntu, but click the option "reinstall Ubuntu" (not "erase disk and install Ubuntu" !).
You are ready! Your Ubuntu OS will work, but your Windows-not. Before clicking the file to install Ubuntu, click Files->Computer->home and copy all your files: Documents, Downloads, Pictures, Music, Desktop and Videos. Copy them on another flash drive or SD card to backup your files (or copy them on "Google Drive" or other similar site).
To make your Windows work too, do the absolute same, as to make your Ubuntu work! Just empty the flash drive with Ubuntu OS and install on it Windows OS. On the other flash drive, with your Ubuntu documents and etc. , or SD card, make another folder for the files from the Windows system.