dopo aggiornamento ubuntu non si avvia windows 7

Aggiungo una parte del report di Booinfoscript

=> Windows is installed in the MBR of /dev/sda. => Grub2 (v1.99) is installed in the MBR of /dev/sdb and looks at sector 1 of the same hard drive for core.img. core.img is at this location and looks in partition 97 for .

sda1: ______________

File system:       ntfs
Boot sector type:  Windows Vista/7: NTFS
Boot sector info:  No errors found in the Boot Parameter Block.
Operating System: 
Boot files:        /bootmgr /Boot/BCD

sda2: ______________

File system:       ntfs
Boot sector type:  Windows Vista/7: NTFS
Boot sector info:  No errors found in the Boot Parameter Block.
Operating System: 
Boot files:        /bootmgr /Boot/BCD /Windows/System32/winload.exe

sda3: ______________

File system:       ntfs
Boot sector type:  Windows Vista/7: NTFS
Boot sector info:  No errors found in the Boot Parameter Block.
Operating System: 
Boot files:        /bootmgr /boot/bcd

sda4: ______________

File system:       vfat
Boot sector type:  Windows 7: FAT32
Boot sector info:  No errors found in the Boot Parameter Block.
Operating System: 
Boot files:

sdb1: ______________

File system:       swap
Boot sector type:  -
Boot sector info:

sdb2: ______________

File system:       ext4
Boot sector type:  -
Boot sector info:
Operating System:  Ubuntu 18.04.1 LTS
Boot files:        /boot/grub/grub.cfg /etc/fstab