The options of the main page of router do not appears so I can not configure the router and cant change any thing

You can also configure it with below method.
Connect your router to computer with ethernet cable then you can access it with following default link. http://192.168.1.1 or http://192.168.0.1 or http://192.168.15.1 or http://192.168.2.1 If you are not able to access it with above ip then check your computers ip address gateway ip is your router ip try with it. Then it ask for user name and password. Type user as "admin" and password as "admin" or "password" or blank. Then you can see configuration page of router. If you are still not able to access router with above ip then you need to RESET it for that press RESET button for 10 seconds it is in back side of router then all settings defaults..Then you can access it with above method. Then click on WAN settings set it as your internet service provider settings enable DHCP Then click on wireless and enable it. . Then click on wireless->wireless security->WEP security there is code password note down it or enter new password then save setting s and restart router. then you can connect wireless with new password. Let me know if you need further assistance. Thanks for using FixYa.