When I turn on my laptop I get a message "inaccessable boot device"

1) Restart the PC and as soon as Windows 10 tries to load; hold the Power button to force shutdown. Repeat this process three to four times, and Windows should automatically load the Boot options.

When Boot Options menu appears, you need to do the following:

Choose Troubleshoot > Advanced Options.

Select Command Prompt from the list of options.

When Command Prompt appears, enter the following lines and press Enter after each line in order to run it:

bootrec.exe /rebuildbcd

bootrec.exe /fixmbr

bootrec.exe /fixboot

2) Another steps from the Boot options where you can troubleshoot many Windows problems. Go to “Troubleshoot -> Advanced options -> Startup Repair.” When you click on “Startup Repair” Windows will restart and scan your PC for any system files it can fix (Microsoft account authentication may be required). If it finds a problem, it will automatically fix it.

3) If Windows is damaged to a point where you cannot access Boot options or Safe Mode, then a Recovery Drive will be able to help. You will need a USB drive and a PC running the same Windows version as yours. Attach the USB drive to another Windows 10 PC, and follow the instructions provided by Microsoft to create a recovery drive.

After creating the recovery drive, attach it to your PC and start it. It should start from the recovery drive and give you the options to solve the problem. You can restore or reset the PC, restore from a system image or even use the command prompt.