I'm sorry to hear that you accidentally deleted important files from your Seagate backup, OneDrive, and computer. Data recovery can be a challenging process, but there are a few options you can try.
First, it's important to stop using the affected device immediately to avoid overwriting any data that can still be recovered. Then, you can try using a professional data recovery software such as EaseUS Data Recovery Wizard, Disk Drill, or MiniTool Power Data Recovery. These are trusted and reliable options that many people have had success with when it comes to recovering lost or deleted data.
Another option to consider is hiring a professional data recovery service. While this can be expensive, it's often the best option for extremely valuable data or if the software recovery options don't work.
It's important to note that not all deleted data can be recovered, especially if it's been overwritten or damaged in some way. However, it's still worth giving data recovery software a try before giving up on retrieving your lost files.
I hope this information helps you in your data recovery efforts. Good luck!