your window mechanism simply needs cleaning and greasing. if you plan to DIY and not familiar on how to detach the door sidings, better have it serviced na lang. there are lots of people who just know how to do that. just visit banawe and any shop could do the job for you. madali lang buksan yang sidings ng door panel if you know where the clips and screws are mounted.

The reason why windows become hard to pull up and down is rusting and dirt accumulated in the window riser / mechanism.

keep a WD40 or similar lubricant handy. once you have opened your door panel, you might as well apply lubricants to the joints of your door lock mechanisms as well.