Oy... I hope I didn't stir up too much confusion here. Let me try to take a stab at some of these...
For starters, a few standard suggestions would empty the patch folder (delete the .pat and .rtp file if they exist) and then run uopatch.exe directly rather than running client.exe or starting it with UOAssist. If you are on Windows Vista or 7 I would also try running it as administrator.
That error is client.exe for me, but what do you mean replace it with an unmodified copy? :/
If you're getting the same error as I am (Old File not found. However, a file of the same name was found. No update done since file contents do not match.) it indicates that the file they are seeing does not match the file they are expecting to see and thus they cannot patch it. In my case, it was because I modified the bodyconv.def file so that I would not have to see certain new graphics that I do not care for. If you have not changed client.exe (which I doubt and hope you haven't) I can't tell you what the problem is.
okay, im gonna need some i have no clue what im doing help here. my shortcut says UOSA. i click that and i get the message "network error connection lost"
i NEVER even get a patch screen.
i went to the place mentioned above and there is no error written in that folder?
This sounds like the enhanced client to me and I'm not terribly familiar with it... the advice I'm giving is for the 2d client. Offhand, though, if you're not getting a patch screen it sounds like you may be invoking the client directly. Try going to the folder that UO is installed to and running uopatch.exe to patch it.
I have manage to log in in Enchated client after a few Network connection lost. I also have those 2 path ( 2D client) uosa win_32_7-0-1-1 .pat and .rtp not sure if they should be there. I can't log in using UOA or basic I'm reinstalling UO now. let see if that fix it.
I can't say much about the EC (don't use it much) but if you have those 2 files in the 2d client then it has attempted the patch and failed for some reason. The first suggestion I would give would be to delete the .pat and .rtp file and then try to start UO again (which will force it to re-download the patch.) If that doesn't work you're going to need to open a file named patchlog with notepad. It can be found in the root of the Ultima Online folder and should say what exactly is failing during the patch.