The inside door panel will probably need to be removed. It's very likely that there will be securing screws at the very bottom of the panel that you can only get to when the door's open...
A car locksmith will be able to open the door for you and possibly fix the lock issue as well.
If you want to try to do it yourself then an Air-Bag (Pump Wedge) can be pushed between door and window glass and pumped up -this will create a gap to enable a wire hook to be poked around to unlock the mechanism.
Amazon £15 AUTOPDR® New Heavy duty Air Wedge Pump Packer for Door Window Car
Amazon £9 Klom Air Pump Wedge Locksmith Tools Lock Pick Set Door Lock Opener
Bent coat hanger - free.