Win7 and Ubuntu dual system, start error: no such partition grub rescue

My laptop installed Windows 7 and Ubuntu dual system, due to company regulations, after installing sandbox software and modifying Win7 partition, I could not start Windows 7 and Ubuntu.
Here is the solution:
First, restore the Win7 system to start.
Use U disk to do a “old peach Winpe” to start disk, specific method see “old peach” official website.
enter winpe, start menu -> “Boot repair”, the window background color is green, select the system is located in the disk character, generally C disk, according to the prompt to operate.
Enter Win7 and restore Ubuntu disk boot.
Open the partition assistant and click “Free partition” to quickly restore boot. The “free partition” is restored to its original partition, such as an ext4 partition.
Restore and boot Ubuntu
1, make Ubuntu install usb flash drive, not Baidu. 2, set the BIOS from the U disk, select try ubunu, do not install.
3, enter the system open terminal
sudo add-apt-repository ppa:yannubuntu boot-repair & & Sudo apt-get update
then type sudo apt-get install-y boot-repair & & Boot-repair
and click the first note: repair
Then it will tell you: Close Boot Security, Retry, just click Yes, wait a few minutes and restart the Ubuntu Boot TAB.

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