@adwaya 

What do you mean by "unable to search device"? 

You mean Tether App cannot find the extender device? or the extender cannot find your router's WiFi signal during the configuration?

Please check if your router's 2.4GHz WiFi is working or not, and also move the extender closer to the home router.

Then please refer to the instructions below to configure it:
Via Tether App: https://www.tp-link.com/support/faq/1373/

Via Web interface: https://www.tp-link.com/support/faq/1400/ 

You could refer to the link below to check if it has been configured successfully and if it is in a proper location:
https://www.tp-link.com/support/faq/2692/

If there is still any problem, please share with me details of the problem and LED status on the extender.