You can "copy or cut" and paste within one project. But you cannot copy and paste between two different projects unless you have Windows and use the ClipMate program in conjunction with Premiere Elements.
And, if you do not want to use ClipMate/Premiere Elements for the copy/paste insert between programs, then...
If you have content from one project and want to get it into another project, you can use selective export of the segment from the first project and then import that export into the second project. We have already discussed the selective export in depth in another of your threads (Work Bar Area gray tabs set PLUS check mark next to "Share Work Area Bar Only" option in the export settings.) Once you have the export, you import that into the second project as source media with the second project's Add Media/Files and Folders.
In your present situation, go back to the first project and use undo to try to bring back the clip on which you used the "cut" command.
Please let us know what is happening. Please do not hesitate to let us know if you have questions on this or need further clarification.
I cannot Undo it unfortunately, i tried that ;/ so worries will just have to re-do it.
i will try the selective import thing now
Selective export to transfer Timeline content from one project to another is all well and good, but, if you have not already, please
check your export settings in project 1 for more than just the "Share Work Area Bar Only" option.
For best results, you want to export your segment from project 1 as a file whose properties are appropriate for the project settings of the second
project. Details of the export settings from the first project may need some consideration.
Please let us know if you are OK with the details.