|Tell us the make and model of your brand name system, or if you have a generic desktop system, the make and model of the mboard. |
The specific model of a brand name system is shown on a label on the outside of the case somewhere, or it can often be determined by going to the brand name's web site and loading a program they have available, if Windows is still working, on the subject computer.
For Dell computers, they have a Service Tag number - the specific model can be determined by using that on their site, or can often be determined there automatically by you downloading some software, if Windows is still working, on the subject computer. The Service Tag number should be on a label on the outside of the case, probably on the bottom on a laptop, often but not always on the back on a desktop, and is often also shown in the bios Setup.
The model, sometimes the make, of a mboard in a generic desktop system is usually printed on the mboard's surface in obvious larger characters, often between the slots.
The model is often also displayed on a logo (graphical) screen early in the boot, but it's often not as specific as the specific model number.
"when I check in disk management it shows Healthy Unknown partition"
Windows cannot show the data on the partition or assign a drive letter to it in My
Computer or Windows Explorer unless it recognizes the software partitioning type used on the partition - it has to use NTFS, or FAT32, or FAT software partitioning, of a type Windows recognizes.
"this lost partition is on another drive"
Is it on a different physical drive ?
Is it on an external hard drive ?
What data is on it ?
Did you make the partition with a different operating system ?
Did you have another - second - operating system on the computer before you formatted C ?
Were you using a third party boot manager program to choose which operating system to boot from before you formatted C ?