Hi Prasad,
You can enable or disable fields in ALV using Layout or Edit(in Fieldcat). Set this as 'X' while you check for your condition.
lvc_s_styl-style = cl_gui_alv_grid=>mc_style_disabled.
Please also check the standard programs BCALV_EDIT_01/02.
Or the blog below:
Disable or Enable Input fields Conditionally In ALV - Code Gallery - SCN Wiki
Regards,
Ashvin