How to get designs that have been deleted and saved?

I made several designs then I deleted one of them and saved it, a few weeks later I need the design back, how do I get it back?

If “Create Backup” option on the General preferences pane is selected/enabled, SketchUp automatically creates a backup file when you save a model.
The backup file is the previously saved version of the file and lives in the same folder as the model file. For example, if your model file is my_model.skp, on Microsoft Windows, the backup is my_model.skb.

If you saved only once, after you deleted the corresponding part of your model, that the skb file contains the deleted part. Rename the skb file to skp (eg. to my_model.skb >>my_old_model.skp) and open it.

( If you saved more than once the the backup file has been overwritten also, will only contains the previously saved state, so most likely you lose your deleted part of the modell permanently. )

Thank you for the answer, but unfortunately it seems i saved more than once so i lose my design

It seems kind of odd that you deleted something from your file and then saved the file and expect weeks later to recover it. What are these designs that you made?