Could not delete partition

I am having a 64GB pen drive with me. The first problem that occurred was that I was unable to format the disk. Then I used diskpart and used the commands clean and clean all. Before completing clean all, I ejected my drive. Then I tried create partition primary and it succeeded. When I gave format command, the same error occurred. Now the drive size has reduced from 64GB to 4Mb. When I now try to list partition, it shows the primary partition. When I tried to delete that partition, I am not able to select it ie. when using the command select partition 1, it shows no partitions selected. Unfortunately I think I have removed the partition table also. When I used 3rd party softwares like AOMEI partition assistant, nothing worked. Is there any solution to restore the size from 4MB to 64GB?

Did you remove the pen drive whilst diskpart was 'cleaning' it. If so, it could have corrupted it. Did you try to run the clean command in diskpart again ?

During clean all command, I removed the usb after closing command prompt. But when I ran clean command again, it didn't show any error.

I was actually facing one more issue. When I tried to format the drive, it also showed a write protected error. But I don't know how to deal with it.

I can only suggest you try MiniTool Partition Wizard to see if it helps:

Best Free Partition Manager for Windows | MiniTool Partition Free

Good luck.