hey if you have the old modpack you need to restart so you can play the new
Install The Nature OF Doom Modpack
Step 1
Installing a modpack using the Technic Launcher is easy. If you don't already have the launcher downloaded, visit our download page to get the latest version.
Step 2
Type in the modpack name (The Nature OF Doom Modpack) or paste the following url into the search box.
Step 3
Finally, click Install at the bottom right of the launcher after you select The Nature OF Doom Modpack from the list on the left. The launcher will handle everything else!