Vista - Dual User accounts problem

When I purchased m computer,it had one account,"home"
I created another one "xyz"
Then after a while I deleted "home"
Then later I renamed "xyz" to "abc" and created a new account "xyz"
After a lot of usage I noticed that "abc"'s account was described as "xyz"
and "xyz"'s as "xyz_2" in C:/documents and settings
Also in My computer, under the heading"files stored on this computer" I
found that when I log on with "xyz" I can access both the user's as well as
the shared documents,but when I open My computer in the"abc" account, I can
only access shared and "abc"'s documents.
After a month or so of usage by my brother, I found that "abc"'s documents
was not present in "xyz"'s account,nor could it be accessed through My
computer-abc's documents in abc's account.
Then I found out that the Account picture that appears at the start
screen(where you select your account and type the password for it)had changed
to the pictures it were a month back(for both accounts).
I feel that a system restore may have happened.
Please give me a solution.