What to do if I was granted 2 weeks of vacation to have an elective surgery and I am now being forced to return to work after 1 week?

While ordinarily, an employer has substantial discretionn as to when to grant vacation, or to even call employees back from days off, if an employee took actions to his or her detriment--like scheduling surgery, which requires time to recover--in reasonable reliance on the employer granting them vacation time, the fact that the employee relied on the promise of vacation time to his/her detriment may make that promise binding. Thus, even though the employer could probably call you back in if you were just taking time off to relax at home, since you had surgery based on the promise of two weeks off, they may not be  able to do this.

However, bear in mind that regardless of your legal rights, if your employer forces the issue--e.g. terminates your employment for not coming in--you'd have to take legal action to vindicate your rights; since that has its own costs, you should consider if you want to do this.

Note that if your employer has at least 50 employees (located within a 75 mile radius) and you have worked there full time (more or less) for a year or more, another option might be to let your employer know you are taking a week off under the federal Family and Medical Leave Act. If you and your employer are both covered, they have to grant you the time and are not allowed to retaliate against you for doing it.