They are aware of an issue with Windows 10 that can cause the Settings app to not launch, or launch the Store instead of Settings.

Update (10/20/2016) – Thanks go to the community for suggesting additional options for adding a new user.  We have incorporated your suggestion for adding a new user through command prompt in the below workaround instructions. If you are still experiencing settings not launching with the Anniversary update, please list your version # in your replies. 

Update (8/5/15) – Today, we released KB3081424, Cumulative Update for Windows 10: August 5, 2015, which includes a fix that will prevent this problem from reoccurring.  This update does not, however, restore the Settings app if it is already experiencing this issue.  After you have run the troubleshooter, make sure you have installed updates to prevent the problem from reoccurring.

Update (06/06/2016): If your settings still aren’t working and you have installed the most recent updates, you might want to try adding a new local administrator account to your device.

Add a new local administrator account to your device:

• Add through the control panel or search for “lusrmgr.msc” and open the Microsoft Common Console Document. Select “users”, right click “users”, choose the option to “add new user”.   Type in the required information
• Add through command prompt as an administrator.
  1. Click Start. In the Start Search box, type cmd, and then press CTRL+SHIFT+ENTER.
  2. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
  3. Type net user username password /add  replacing the word username with the new account username and the word password with a password for the new account that meets Windows 10 complexity requirements.
  4. If successful, Command Prompt will populate a message.
  5. Now, add that newly created account to the Administrators group. Type:  net localgroup administrators username /add  replacing the word username with the new account name created in step 3.
• With Crl+alt+del , select “ Sign out” to sign out of your account and then sign in to your new account.

If you can now open Settings, move your personal data and files to the new account.

Make the new account an administrator account:

• Under Settings à Account à Other users, select the account you created > Change account type.
• Under Account type, select Administrator > OK.
• move your personal data and files to the new account.

If you were using a Microsoft account to sign in before, associate the Microsoft account with the new administrator account. In Settings > Accounts, select Sign in with a Microsoft account instead and type in your account info.