I can give you two options:
Option 1: Reset all styles
This is the easier method. You will, however, lose all custom styling. Make sure to save before doing this.
On the Home tab, click Change Styles > Style Set > Word 2010
Option 2: Change TOC 2 style
You can manually edit the TOC 2 style. It might also be another TOC #, TOC 2 is used by default for level 2 headers.
- Press Ctrl+Alt+Shift+S to open the Styles dock.
- Right click on the appropriate style (TOC 2). You may wish to see the correct one (TOC 1) to compare. If you cannot find the style, click Options in the bottom right of the Styles dock and "Select styles to show:" "All styles".
- Select Modify.
- Click Format on the bottom left of the Modify Style window and select Tabs.
- Select Alignment Right and the dotted Leader.
You may have to play around with those options a bit.