Rich Text Editor Disappearance

I attempted installing & activating some plugins, such as WP Cache, Image Headlines, Breadcrumb, PostAvatar, WordPress.com Stats, AskMe Wp2.1, & All-In-One-SEO-Pack, but all of those either didn’t work properly, didn’t work the way I expected them too, or I just decided to not use them at this time. I did not, however, edit anything in my WordPress templates. Before de-activating all the above plugins, I went to edit a post and realized that my Rich Text Editor was gone- in it’s place was a title ‘post’ and a text box, where I now must input both the text and HTML of my posts. I tried de-activating AND deleting all the above plugins, thinking perhaps one of them, unused, was causing the problem; but it did no good, the editor is still gone.

I apologize if this isn’t very clear, or if there is an obvious solution to this; I’ve never dealt with a WP problem like this before. I appreciate any help. Does anyone know what I can do to get my Rich Text Editor back? (By Rich Text Editor, I mean all the tags you can use when creating/editing a post; there are two different styles, ‘text’ and ‘html’ that you can switch off between, but to write/edit I usually use the fancy one with the bold, underline, link, b-quote, etc. tags. But now it’s disappeared…so I’m kind of stuck.)