I had emergency surgery 4weeks ago after a mower accident while on my period. My period was shaky after that and this month it's 2days late. Normal?

Normal. Many women fluctuate several days early or late with their menses, so with the stress you have been through, 2 days later than expected is not unusual. I hope you have recovered from your accident.
Possibly. Am assuming that you have not been sexually active since your last period. If your body has suffered a significant trauma/ stress - than a period may be late or missed.