Windows Store apps not installing on Windows 8.1 operating system (0*c03f300d)

 "Something happened your Purchase can't be completed Error code (0*c03f300d)

First of all try the Windows Apps Troubleshooter to solve your issue. Here is the download link for that one:

Download Windows 8.1 Troubleshooter. In most of the cases it will fix the problem. 

Download 

 

Just download and run, rest it will manage automatically. In case, above fails, then try creating another account and check whether the issue still persists. Try Reset option from PC Settings. Back up the important data before resetting.

How to Reset Windows 8 and Windows 8.1​

This will show you how to use a new feature in Windows 8 and Windows 8.1 to reset your PC to completely start over back to default to remove all personal data, apps, and settings from the PC, and reinstall Windows. This is like doing a factory restore/recovery on a purchased computer or clean install, but a little faster.

Resetting your Windows 8 PC works like this:

• The PC boots into the Windows Recovery Environment (Windows RE).
• Windows RE erases and formats only the hard drive partition on which Windows 8 and your personal data (user folders) reside.
• Windows RE installs a fresh copy of Windows 8.
• The PC restarts into the newly installed copy of Windows 8.

You must have an administrator account on the computer to be able to reset Windows 8.

 

 Note: Windows 8.1 is not supporting now.

You can still use it but can't get new apps of the store and many difficulties you may face.