A Microsoft file hosting and synchronization service.
Hi, Sandie. If there is no sign in option and it shows offline, reset the OneDrive app. Press Windows key plus R, type %localappdata%\Microsoft\OneDrive\onedrive.exe /reset, then press Enter. Wait about two minutes, then open OneDrive again from the Start menu. This reset restores the connection and brings back the sign in screen without removing your files.
If it still stays offline after the reset, let me know what exact message you see. Thanks!