i cleaned rust from the pcb
Rust on PCB indicates water damage or the very least, too high moisture environment.
i opened the hdd(i had mask,gloves,special tools)
Unless the room where you were, when you opened your HDD, isn't hermetically sealed dust- and static-free clean room, your HDD is good as gone. Since there are dust particles in regular air which now got inside the HDD, including on the platters and you've contaminated the HDD internals.
Most physical damage cannot be repaired by end users. For example, opening a hard disk drive in a normal environment can allow airborne dust to settle on the platter and become caught between the platter and the read/write head.
During normal operation, read/write heads float 3 to 6 nanometers above the platter surface, and the average dust particles found in a normal environment are typically around 30,000 nanometers in diameter. When these dust particles get caught between the read/write heads and the platter, they can cause new head crashes that further damage the platter and thus compromise the recovery process. Furthermore, end users generally do not have the hardware or technical expertise required to make these repairs.
Consequently, data recovery companies are often employed to salvage important data with the more reputable ones using class 100 dust- and static-free cleanrooms.
If the data on your HDD is valuable for you, your best bet getting it is bringing your HDD to data recovery firm. Depending on how much additional damage you created by opening up your HDD, the price of data recovery can easily skyrocket.
Btw, i've had two WD 500 GB HDDs die on my with relatively short period of time and from now on, i'll avoid 500 GB drives from WD. Though, the 1TB WD drive [WD10EZEX] has really good reliability and i've several in use, for many years, without issues.