Help! Accidentally changed default programme to open .pack files to Internet Explorer!!

[SammyTotoro]

Please help me. I have somehow (and don't ask how but do feel free to tell me I'm an idiot and take away my mouse and keyboard until I learn to use them properly!) managed to click to use Internet Explorer as the default programme to open all steam (and probably just all) .pack files. My other half has a lot of MODS for his Total War Warhammer and I'm desperately trying to find a way to change the defult programme back or solve the problem in some way so he can get back to his favourite game. Please help me, I will be forever in your debt.

Thank you very much for any help you can offer.
Sammy :)

[76561198218426745]

Control Panel > Programs > Default Programs

Instructions for Windows 10, specifically.
https://www.howtogeek.com/223144/how-to-set-your-default-apps-in-windows-10/

[SammyTotoro]

Alas it's Windows 10 and that just gives me a load of apps and Microsoft programs to choose from. Could you advise exactly what program should be being used to open the .pack files?

[76561198218426745]

Unfortunately I don't know what program, specifically, Total War: Warhammer uses to open .pack files. You might be able to find out if you ask on the game's forum:
http://steamcommunity.com/app/364360/discussions/

Some cursory research suggests the game's executable itself is what the file is meant to be associated with.

[SammyTotoro]

Thanks for the help guys, we're all set with how to change the default programme but still just no clue about what programme should be being used to open the pack files to make sure they are being accessed correctly by the game.