You can try these methods to fix invalid partition table:
Solution 1: Rebuild the MBR with PartitionGuru
Since the PC cannot boot to system now, the MBR rebuilding should be down under Windows PE environment.
Step 1: Create WinPE bootable USB drive of PartitionGuru.
Step 2: Boot your computer from the bootable USB disk.
Step 3: Rebuild MBR (Master Boot Record).
Solution 2: Rebuild MBR using Command Prompt
If you have a Windows installation disc, you can fix invalid partition table via Command Prompt, here are solutions:
Step 1: Insert installation disc into your computer and boot PC from the disc. Click “Repair your computer”
Step 2: Select Command Prompt in the “System Recovery Options” window.
Step 3: Type “bootrec.exe” in Command Prompt and press “Enter”.
Step 4: Type “/FixMbr” on Windows. Restart computer and check if the issue is fixed.
Solution 3: Change the boot sequence
If your computer contains more than one local disks or external disk, many times, the invalid partition table is likely to happen due to incorrect boot order. On such occasion, you should restart your PC and enter Boot Menu where you can set disk boot order. Make sure your computer is booted from correct disk, save changes and restart computer.
If one of these works on your computer, you may need to reinstalling Windows to the fix invalid partition table problem.