Hi,
Lokks like your machine runs Windows 8.1. Well, you've deleted the app. Pleae try (for Windows 8.1):
(a) Hit Win key, you can see many icons there,
(b) Wipe (or scroll) to the next RIGHT screen, you can find Microsft Office there
(c) You can right click any application (Word, Excel ...) and send it back to Start screen OR pin it to the Taskbar
Regards.