For 99% of users: Use the built-in PC Settings > Region and language method. If that fails, your Windows RT device is likely locked to its original language permanently.
: You must have the Windows 8.1 Update (KB2919355) installed before you can apply certain language updates. windows rt 8.1 english language pack download
Disclaimer: Windows RT is obsolete. This guide is for legacy support and educational purposes only. For 99% of users: Use the built-in PC
You cannot download this from Microsoft’s official website anymore. You need a trusted third-party archive of Windows 8.1 RTM language packs. Disclaimer: Windows RT is obsolete
Search for a file named: lp_en-us_81_cab.zip or en-us_lp_8.1.cab
: Sign out and sign back in for the changes to take effect across the entire system UI. Essential Updates and Prerequisites
: Swipe in from the right edge of the screen, tap Settings , and then tap Change PC settings . Select Time and language , followed by Region and language .