Windows 10 I believe 

*edit to reply*. I didn’t install an OS on the New hard drive.   I unplugged the old HD and plugged the new one in.   Haven’t been able to get the laptop booted yet to install a new OS.  Windows 10 was on the old HD

Welcome to the Dell Community @DDB from YYC 

What Operating System did you install on the new hard drive???

Best regards,

U2

How to Download and Use the Dell OS Recovery Image in Microsoft Windows:

https://www.dell.com/support/article/en-us/sln299044/how-to-download-and-use-the-dell-os-recovery-image-in-microsoft-windows?lang=en

@DDB from YYC 

Did you install a Dell Recovery Image or did you use a W10 media created image???

Regards,

U2

No I didn’t do either.  I will try the OS recovery tool

Your very welcome @DDB from YYC 

Regards,

U2

@DDB from YYC 

You have to boot from a Dell USB recovery image.

How to Download and Use the Dell OS Recovery Image in Microsoft Windows:

https://www.dell.com/support/article/en-us/sln299044/how-to-download-and-use-the-dell-os-recovery-im...

Regards,

U2

Create Windows 10 installation media:

https://www.microsoft.com/en-us/software-download/windows10

Thanks so much.   Will try this and let you know.  Appreciate the info. 

finally got around to this.......and omg that was so easy and it worked!

thanks so much!