Hi,
I would like to help!!
Please follow the steps below.
Insert the Windows installation disc in the disc drive or connect USB media, and then start the computer.
Press a key when the message Press any key to boot from CD or DVD appears.
If your PC does not detect the media automatically
During the restart process, read the screen for any instructions that explain how to interrupt normal startup and enter the basic input/output system (BIOS) setup utility. Most PCs use the F2, F10, ESC, or DEL key to begin the BIOS Setup.
Look for a tab in the BIOS Setup Utility that is labeled Boot Order, Boot Options, or Boot. Following the directions on the screen, use the arrow keys to go to the Boot Order, then press Enter.
Locate the CD, DVD, or USB flash drive (this might be called Removable Device) in the Boot list. Following the directions on the screen, use the arrow keys to move the drive up so that it appears first in the Boot list. Press Enter. The boot order sequence is now changed to boot from the CD, DVD, or USB flash drive.
Press F10 to save your changes and to exit the BIOS Setup Utility. Select Yes in the confirmation window. The PC will restart. Allow the PC to restart normally. The scan will take a few minutes and remove any malware that may be infecting your computer.
On the Choose an option screen, select Troubleshoot. Select Advanced Options >Startup Repair
Click the operating system that you want to repair, and then click Next.
Click Repair your computer.
Select a language, a time, a currency, a keyboard or another input method, and then click Next.
If it doesn't fix the issue then go to Command Prompt under Advanced Options.
Type Bootrec /RebuildBcd, and then press ENTER. This command will rebuild Boot Configuration data by scanning all disks for installations. Doing this will fix any damage to boot sector, which actually require for booting into a PC.
please let me know if you need further help!!