I found that a lot of the vocab words on my test were in the Mometrix HESI A2 study guide. There were not as many in the Elsevier book but I bought both of those and also purchased the Pocket Prep App as others have recommended. It's a little expensive but very worth it.
For the vocab, I would try to learn all you can through memorizing the words in the books, but also try to look for context clues in the sentences. Most of the questions have a hint somewhere else in the sentence and when I didn't know a word, I tried that and it helped. Also, most of the words were in some way related to the medical field and they use a lot of common latin origins, you could try looking at those too!
It's hard not to get frustrated, I'm sorry this happened! Try to set up a schedule for yourself to do a little bit each day. Unfortunately, this is really not a test that many can cram for, there is just too much information. I would suggest starting at least a month before the test. Take as many practice tests as you can and just try to go into the test as confident as you can. Best of luck on your next test!!!