Is it still possible to download the previous version?

[Alloronan]

I updated to the latest version on my desktop to have a look, thinking I still had the old version on my laptop and could change back if I wanted to. Unknown to me, my boyfriend had borrowed my laptop and had updated it to play with his friends. Now I can't get back into my friend's servers, who hasn't updated. Does anyone know of a reliable place where I can get the previous version?

[Valkon]

Just go into your modpack options (click the gear under the modpack on the left), select the "Manually select a build" option, and pick the build the server uses in the drop-down menu.

[Alloronan]

Didn't know that was possible, thanks!