You guys are the best! In desperation, I called Apple tech support last night. I really thought that my iPad was gone for good (and was a little embarrassed that I felt so panicked at the thought). After initially speaking to a tech support guy who said that he would "look it up," I spoke with a supervisor who advised me to do just what you said (hold down the sleep and home buttons simultaneously till the Apple logo appeared – I now know that this is a hard reset).
So my iPad has come back from beyond. 
Thanks again!
Anne
__._,_.___
MARKETPLACE
.
__,_._,___