1 – Click the “Start” button in the lower left part of the screen to open the Start menu.
2 – Click “Run” and type “regedit” into the field.
3 – Click “OK” to run the Windows Registry Editor.
4 – Expand the listing for HKey_Current_User by clicking the plus symbol.
5 – Continue expanding the registry tree until you have opened HKey_Current_User/Software/Microsoft/Internet Explorer/Main.
6 – Look to the right-hand section of the window and highlight the entry “Window_Placement” with a left click. Right-click to bring up a menu and click “Delete.” When you restart Internet Explorer, its window size will reset to default.