The 4gig Patch applets are not for Windows. They're for the SH4.exe. It is a 32 bit app, and by default is written to only access less that 2gig of memory. The 4gig Patch flips bits in the executable file that shows Windows that the app can properly address more than 2gig of ram, therefore, the 64-bit OS will then let the program access said RAM. That's all it does, is flips bits.
As for the SH4 working previously, and now it's not, I will now hazard a guess that you have Windows 10, and it just updated itself, trashing your DirectX 9.0c and all of your older games, if you have any others besides SH4. I cannot get my SH4 to run at this time on my Windows 10 laptop either... fix unknown at this time. This might also be why your UPlay download is failing... Have you tried running the game without any mods yet?
