Brother MFC5840CN scanner driver

I've had this installed and working under Ubuntu 9.04 using XSane 0.995. I believe it was installed as an USB unit also. The upgrade to XSane 0.996 seemed to cause it to stop working.
Don't know why that might happen.
The error message that I am now getting instead of being able to scan with it is "no device available/supported device is busy". The Brother site says that command line is required for installation of the driver. I'm trying to remove everything to do with the install and re do it underXSane 0.996. I presume this is what it needs.
I can't remember if I installed it via command line or using synaptic. {I've tried it so many ways and on several different installs it's hard to keep them all straight}. BTW; I'm rather limited in how much command line I am able to do due to dementia.
A problem that I am having now with either 9.04 or 9.10 Ubuntu is that when I try to install via command line and using su or sudo it's not recognizing my password and I am unable to install with super user privileges. I believe I've also encountered password recognition problems with using synaptic also....
I just don't know how to figure out what to do to get privileges to reinstall drivers. Installing them Synaptic way is not working either.
In fact my dementia is even now making me fuzzy thinking about what I'm doing typing this. I can only stay focused for so long and the more complicated things are the shorter the attention span. Oh well I keep plugging anyway. Any help with why password doesn't work with su or sudo?
I kind of need some help laying it all out so I can copy and paste into terminal to get it all done if that's possible. I'm not sure I covered all the bases but will be back another day to check and modify if needed. Hope this was understandable? l8r\%:)SW