I need a formula for Google sheets

Hi!

I need a formula for google sheets to change text within a cell.

Current text is:
https://drive.google.com/open?id=1yoVEWEbV6XFnaQrG11RKZWj_hzYJfoZ&usp=drive_fs
Change to:
https://drive.google.com/file/d/1yoVEWEbV6XFnaQrG11RKZWj_hzYJfoZ&usp=drive_fs

So, change the part (open?id=) to (file/d/)

Links above have one letter missing but this is towards end so won't affect the formula. I have circa 200 cells to change. All are same text up to point of open?id so one formula will do it.

Need done asap please.

Thanks!