Hard disk drive is not showing up on disk management or on my computer
Did it before? What occurred leading up to the disappearance? Is it the primary HDD (boot for OS) or a slave or an external? What is it's model and how does it connect? Does it 'spin up'? Any other details...like loud sounds on start, grinding noises, beeps, clicks, squeals? What flavor Windows? How long installed? Any other system failures? Any important facts (like it dropped to the floor, etc)? Please check Event Viewer for any interesting 'errors' (skip restarts after lost power, unexpected power downs and OOBE).
Its a Toshiba HDD and it can be connected with samsungs connecting cables and it is windows 7.
I changed the ram few days ago computer was acting funny for a few days after that the hard disk wont start I tried doing many things on the internet still I dont understand the problem
Its external hard drive and it didnt fell or anything
Trying to piece together what you are telling me..
You have a Samsung something (model?) with Windows 7 OS on its primary boot HDD and an external Toshiba HDD (model? connected by USB? with external power or powered by USB?).
You 'changed ram' (added? replaced? with what?) in the Samsung something and the Samsung something started behaving strangely (in what way? beeps? noises? crashes? flashing lights?).
"after that the hard disk won't start" - the internal primary or the external or the entire system?
"I tried many things on the internet" - tests? utilities? repair? recovery? new drivers? malware scans?
Please clarify and also describe what still actually works properly (can you start your system? will it load Windows? can you reach the internet?, etc)
First step is to determine what works 100% properly and to try to protect that from damage...by backing up files, etc.
What is the computer used for? Have you made backup copies of any important files?
ps Please punctuate if possible.