I just install Ubuntu and I'm having problems booting into any operating system. I'm currently on the live USB and I was looking around on the hard drive. There is a partition called ESP which has a folder called EFI/Boot. I am assuming this is where the Windows system boots from. If I look in the RECOVERY partition, there is another folder called BOOT, but it is empty. I cannot boot into any partitions and I would like to boot into the recovery partition to hopefully restore my system. Can I copy the ESP bootx64.efi file into the recovery boot folder?
On UEFI booting starts with .efi files only from EFI System Partition(ESP).
ESP on UEFI/GPT disk is the equivalent of active partition on BIOS/MBR style disk for Windows 7/8.
So you would not repair booting copying files from ESP to any other partition on a GPT disk.
The simplest way for repairing Windows 7/8 booting is to use a Recovery CD/USB - you can prepare it on another computer. This recovery CD/USB should be the same version as the installed Windows OS - for example Windows 8/64-bit!
It is a good practice to have a Recovery or Live CD/USB for every installed OS on your computer for emergency.
Creating/installing/configuring a recovery partition without a running Windows OS is almost impossible.