So, a while ago I dropped my valuable power tool in the nether by accidentally pressing Q and it fell into the lava so I needed to craft and upgrade a new one. Of course I don't want that to happen again. My question is if it would be possible to block the drop key for the power tool so that when I press Q it doesn't drop, but when I press it with an other item in my hand, for example dirt, the dirt blocks would still drop. I am using the direwolf20 modpack.
It is not possible to do that in vanilla Minecraft. Minecraft doesn't care what type of item it is, and will throw it all the same. It wouldn't be too difficult creating a mod which only lets you drop blocks, not tools, but you would need to contact a modder for this feature; as far as I know there are no existing mods with this capability.
I have run into this same problem, and have avoided the issue by going into the settings and changing the "drop item" key to something like G or P, making it much more difficult to hit the key by accident.