Story Points - How we will consider the story points in the Sprints

Hi All, 

I would like to bring up this example and take your inputs.

Example : I have a one User Story and assigned 4 Tasks to complete the User Story. 

Now we have assigned Story Points to all the Tasks (assuming 2 Story Points to the each Task) and taken this User Story in the Sprint Backlog.

Development team has started working on the tasks and they were able to complete only 2 Tasks within that Sprint but Development Team has worked on the remaining 2 tasks and completed 50% of the work in the current sprint itself, due to Tasks are incomplete, Development team has moved the remaining 2 tasks to the next sprint.

My Question or Doubt : For the next Sprint Planning, how can we consider the Story Points ? Is it 1 Story Point or 2 Story Points ?? 

In the previous Sprint , already Development team has spent 50% of their time and completed 50% of their work as well, then I assume we need to consider 1 Story Point instead of 2 in the current sprint. If we say 1 Story Point , then how can we measure or track the previous 1 Story Point which Development Team has spent in the previous sprint.

Please provide your thoughts.. Looking forward..

Thanks & Regards,

Suresh Prabhu.