if it is very important,you may ask for help from the moderator.

One thing I often do is include one or two keywords that you remember including in your post.

Then, on top of that, include your ATS name..

For example, in 2008 I made a post about Pulse Detonation propulsion.

Under the search menu I would just type in "Pulse detonation and BlasteR".

Your old posts are usually very easily found that way.

You might only remember one or two words from the thread title. You might only remember the name of the OP or thread author.

In that case you can type in your own ATS name and the name of the OP or those one or two words you remember and 90% of the time the post you're trying to remember will be on the first page somewhere.

-ChriS