My DNN site is hosted by fast2host.com and I tried upgrading to 4.9.1 last night.  Backed up everything in root by making copies of all folders (wwwroot, db and logs), downloaded 4.9.1 and extracted it, then copied to host.  Changed lines in web.config to reflect mysettings.  Tried to connect to siteand nothing happened.  So in frustration I put everything back as it was by deleting the new installand renaming the old folders back to their original names.  Now the website is visible but the log in module has disappeared so I can't log in!  So can anyone help with the problem of getting my login module back and once I can get in again, help with a Dummies guide to upgrading from 4.5.0 to 4.9.1 (or 5.0.0 if its worth going all the way)

I think the login is/was a module.

Tried saving web.config no good

Tried to revert back to old version of DNN but got nowhere.  Sit not found errors etc etc.

Tried to do clean install of 4.9.1 and didn't work.

Finally in desperation I deleted the database and installed 5.0.0 (maybe stupidly).  After a few attempts it installed fine, but now I find that some modules don't work - Store, Map, maybe others I haven't tried all.  Seem to get same type of error with all modules.

A critical error has occurred. Method not found: 'Void DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(System.String, DotNetNuke.Entities.Modules.PortalModuleBase, System.Exception, Boolean)'.

So my next question is, is it even worth trying to downgrade to 4.9.1 from 5.0.0... and if I did do it would I lose the look/feel that I now have with version 5?

Help?