Lost password to Apple ID and Find My IPhone I have Find My iPhone turned on and I know what Apple ID it uses. But lets say I forgot the password to my Apple ID and lost my phone? Will I still be able to find my iphone or activation lock it if I reset my Apple ID password on the Apple website? Or will I have to relog with that Apple ID on the device?!
First let's solve the Apple ID problem. You can start the password reset process from the official Apple ID website, this also can be done any device as long as you have a web browser:

Step 1:Go to this Apple ID site and under “Manage your Apple ID” choose the “Reset your password” option
Step 2:Enter the email address associated with the account and answer the security questions as usual to complete the password reset process

Second Lost iPhone problem:
You can use Find My iPhone to find your device and take additional actions that can help you recover it and keep your data safe.

Step 1:Sign in to icloud on a Mac or PC, or use the Find My iPhone app on another iPhone, iPad, or iPod touch.
Step 2:Find your device. Open Find My iPhone, and select a device to view its location on a map. If the device is nearby, you can have it play a sound to help you or someone nearby find it.
Step 3:Turn on Lost Mode. Using Lost Mode, you can remotely lock your device with a four-digit passcode, display a custom message with your phone number on your missing device's Lock screen, and keep track of your device's location. If you added credit or debit cards to Apple Pay, the ability to make payments using Apple Pay on the device will be suspended when you put your device in Lost Mode.

If you use Family Sharing, any family member can help locate another member’s missing device. Just have your family member sign in to iCloud with their Apple ID, and you can find any device associated with that Family Sharing account.