i need to change my phone language as my iphone 4s is locked

See this document If your Apple ID is locked or disabled https://support.apple.com/en-us/HT204106 

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And see If you forgot the passcode for your iPhone, or your iPhone is disabled https://support.apple.com/en-us/HT204306

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But, are you seeing activation lock? If yes, see: See Turn off Activation Lock https://support.apple.com/en-us/HT201441. All possibilities related to iPhones, iPads, and iPods are covered here except the case of inheritance.

Since you must have acquired your device second hand, you usually will need to obtain the needed password from the person that last set it up. If you can’t obtain it, in the rare case your device came activation locked from an authorized Apple seller, then contact Apple Support and present your original purchase receipt for your device with the device’s serial number on it. You’ll need a photo ID too. If you can do neither, then the device is useless to you.

You can use the suggested support options below if you have the needed receipt. Alternatively, if an Apple Store is open in your area, then you can go there to deal with your problem. In this case, you can make a genius-bar appointment (https://www.apple.com/retail/geniusbar/) if you want.

Get a call from Apple support to help solve your problem using this

link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific andregion-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help https://getsupport.apple.com/. Go through the options to find the best support option.

How is your phone locked? Disabled? Your Apple ID won't work? More information would help.