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If you dropped out of view altogether it's unlikely that anything on-page alone could restore rankings. On-page only counts for a limited percentage among all the scoring criteria used. Off-page factors weigh heavily and it's unlikely that any software whatsoever could replace human eye research and analysis of that.
Lack of a meta description wouldn't cause it but if you used that software to query Google that could account for the drop.
If you come up you are in Google and need to do more SEO. If it is not then you may need get more links and stop any SPAM things. If you do a site:domain.com -asdf and you find all your pages you might want to do some Title work. Remember the H1 tags and keyword density. Rename a page or create a new page to keyword.asp. If it is a keyword phrase do keyword-phrase.asp.