If your Apple Watch is dead and you cannot turn it on, there are a few things you can try to locate it:
Check the last known location of your Apple Watch: If you have the Find My app set up on your iPhone, you can use the "Find My" feature to try and locate your Apple Watch. The Find My app can help you locate your device if it is nearby and connected to Wi-Fi or cellular data. To use this feature, open the Find My app on your iPhone and select "Devices" at the bottom of the screen. Then, select your Apple Watch from the list of devices. If your watch is nearby and turned on, you should see its location on a map.
Check the location of your last known connection: If your Apple Watch is not nearby, you can try checking the location of the last device it was connected to. To do this, go to the iCloud website and sign in with your Apple ID. Then, click on "Find My" and select "All Devices" at the top of the screen. Select your Apple Watch from the list of devices, and you should see a map showing the location of the last device it was connected to.
Use the "Ping" feature: If you are unable to locate your Apple Watch using the above methods, you can try using the "Ping" feature to help you find it. To use this feature, open the Find My app on your iPhone and select your Apple Watch from the list of devices. Then, tap the "Actions" button and select "Ping." This will cause your Apple Watch to emit a sound, which may help you locate it if it is nearby.
Ask for help from others: If you are still unable to locate your Apple Watch, you may want to consider asking for help from others. For example, you could ask friends or family members if they have seen your watch or if they can help you look for it. You could also consider reaching out to the authorities, such as the police or lost and found, if you think your watch may have been stolen.
I hope this information is helpful! If you are still unable to locate your Apple Watch, you may want to consider contacting Apple Support for further assistance.
