I've seen enough "bug reports" of mods not working because of naming conventions, so I will explain these here briefly:
- Modpacks folders can be named with any name, but the subfolders inside must follow naming conventions
- Mods must have a name corresponding to the nodes/items/etc. they define: the folder of a mod that creates a node called "mymod:mynode" must be named "mymod".
How to know if the mod error is due to naming conventions:
- Look at the terminal/console in which Minetest is launched, if one of the lines printed is "mod does not follow naming conventions", then the bug is there.
- Look at debug.txt and see whether you find the same line at the end.
- If it is not due to naming conventions, then you can post a bug report in the mod's thread.
How to know the name to give to the folder:
- Look at the topic where you downloaded the mod; the name of the mod should be inside brackets in the title (for example, [mymod]). Moreover, you can also learn whether it is a mod or a modpack: mods should have [Mod] in the title, whereas modpacks should have [modpack]
- If that is not enough, look at the folder of the mod/modpack: if it contains a file "modpack.txt", then it is a modpack, and you don't need to cahnge its name; else it contains a file named "init.lua". You can then examine the files to find a register_node, register_craftitem, etc. to find the name of the mod.
- Also, you can avoid renaming the folder by putting a file named "mod.conf" and with content "name = <modname>", where <modname> is the name of the mod. If such a file does not exist, you should ask the mod developer to add it.
Furthermore, modders and users should never use generic programs such as Notepad, but rather Wordpad, or a program that's designed for editing code, when composing a mod or modifying something they downloaded.