Here is small tip to help you distinguish them.
Look at the gap. If it can be filled with the word "what" then what you are missing is the noun:
it was due to her own....(what)?... carelessness (noun)
if the gap can be filled with "what kind" you are missing an adjective
it was due to her.......(what kind) ....actions. careless (adjective)
if the gap can be successfully filled with "how" you are missing the adverb
it was due to the fact she was acting ..............(how?) .... carelessly
if the verb is missing the gap can be filled with "what did he do"
she .............what did she do ............carelessly acted (verb)
Hope it helps you tell them apart