Created new partition using Hirens tool....Now Ubuntu wont boot

Hi All, was wondering if you could help, apologies if this has already been answered.

So my laptop has a 500GB HDD. The only OS installed was Ubuntu.

I decided to boot from Hirens USB and used a partition tool to create another partition (it was my intention to install Windows on this second partition)

Now, when I am booting the laptop it is stuck at "GNU GRUB" screen, with the grub> prompt.

I understand the MBR may have been corrupted or needs to be reconfigured

any help is appreciated....really dont want to format the drive again as there is some data I need access too.

Thanks in advance