How many watts does tweeter needs
Sensitivity - 98dB/W/M


OK, so it's a PA or horn speaker, so the tweeter will be compression or piezo.

Maybe the problem isn't the tweeter. Disconnect it and wire it to a headphone jack, which you plug into your PC's line out, and then play some music through it. Tweeters can be destroyed by low frequency, so don't use a power amp for this, the line/headphone output of your PC is fine, as it doesn't have enough power to harm it, you can connect the tweeter directly. 

If it works, check the wiring and crossover.

If the tweeter is indeed dead, you'll have to replace it with the same model, unless you want to redo the crossover calculations which depend on the tweeter efficiency and impedance. So look for a manufacturer reference on it. 

Unless it's a piezo on a low-cost PA speaker which will sound like junk anyway, in this case you can use something vaguely equivalent. 

Without more information (like pics, loudspeaker brand and model, documentation, etc) can't say more.