I am trying to scan a document. I have Windows 7 and use Internet Explorer. My printer is a HP Officejet J4680 All-in-One. It is hardwired and I have AT&T Uverse as my Internet service. I keep getting the message that my device is not connected and yet I am able to print & fax but NOT scan. Does anyone know what the problem is? I do not have much knowledge about computers.
As Jan says, the different functions of an all-in-one device are completely separarate. It is like having a separate scanner, fax and printer all placed into one box. In fact, I've even seen devices (OKi, Brother) where the scanner has a different network identity than the printer... My guess is that the system identified the printer automatically, but that your scanner software hasn't been installed properly (or it has, and it's gone wrong, that also happens). My advice would be to download the full software package from HP (see links in Jan's answer) and install the lot. This will almost certainly resolve the problem.
Try using Paint, available in the Accessories folder in the Start Menu. Once open, click the blue tab with the down arrow (the "File" button), and see if you can select "From scanner or camera". If you can select it, try to use it to scan something from your printer. If anything, at least this method can be used for scanning documents and pictures.
HP Officejet J4680 All In One will not scan
http://h30434.www3.hp.com/t5/Scanning-Faxing-and-Copying/HP-Officejet-J4680-All-In-One-will-not-scan/td-p/1663519
Printing, faxing and scanning are three completely different things so it's not unnatural that you can do one but not the other.
general suggestion:
1. disconnect the printer from your computer
2. uninstall the hp printer driver
http://h10025.www1.hp.com/ewfrf/wc/document?cc=fr&dlc=fr&docname=c02259020&lc=en&product=3692888#N393
3. connect the printer using USB (ignore any automatic installation/driver search Windows might do)
4. download and install the FULL feature software & driver suite
http://h10025.www1.hp.com/ewfrf/wc/softwareCategory?cc=us&lc=en&dlc=en&product=3692888
If it still doesn't work try running the hp Print and Scan doctor utility. To the best of my knowledge it should be installed with the driver suite but you can download it via the link above too (under Diagnostic tools)