changing to Lion

I have made three mistakes and don't know how to undo them.

1. I failed to do a backup before changing my system. Theoretically there are regular
backups but I didn't check when the last one was and sometimes it's weeks.

2. I didn't check what the reviews were on the different MAC operating systems.
Instead I just acted as if I was doing one of those common upgrades we do all the time.

3. I was offered an online version of Mountain Lion to upgrade my MacOs, and I started
to do it. I soon realized that it had a lot of of features I didn't like, but by then the change
had started. So I just did a shut down. Now I can't use my computer. What a mess.

Today, 03:51 PM

I have made three stupid mistakes and don't know how to get out of them.

1. I did a change in OS without checking whether a recent backup had been done.

2. I was offered a Lion download, so I acted as if it was a trivial upgrade and changed from Leopard to Lion without checking reviews of Lion.

3. I saw that there were lots of changes I didn't want and so I just shut the IMac down
in midstream.

a. Hundreds of my simple download files, like recipes, are in BBedit not Word to save
space. BBEdit has vanished.

b. My calendar is in PalmPilot. That is crossed out and a less legible one substituted.

c. My mailboxes have disappeared so my mail is a mess.
Now I have no idea what to do. I can't use my IMac any more, even though a lot
of my life is uniquely stored there. (At 85 that is a lot)..

First, Welcome to our Forums.

I merged both of your posts together as one post in order to keep things all in one place. Posting the same subject to two different forums just causes confusion and unnecessary replies. OK, let's see if we can help you out.

You state that you were offered an on line version of Mountain Lion. Since you were previously using Leopard, you did not have access to the Mac App Store which is the only place you can download Mountain Lion from. Who and where did this offer of downloading Mountain Lion come from?

And since you "killed" the upgrade without it finishing that likely also destroyed or made your copy of Leopard unusable. The only way you can get your Mac back to operable status is to reinstall with your original copy of Leopard. If you have no backups, that means you will have lost all your data.

Plus, the changes in Lion and Mountain Lion are not that drastic.

Unless of course your Mac (not MAC) does not meet Lion's specifications.