Ur mob need to be rooted......
>Install Root explorer from google play ...
>open the app...Go to \System
>Open Build.prop in text editor (take backup before editing)
>Search for curlockscreen=102 (which is ur default lockscreen ,sliding vertical)
>Edit the value to 2,3,4,5 as u wish or simply type "no" (i.e curlockscreen=no)
>save and exit
Reboot ur mob .. u will get lockscreen sliding horizontal.....