Can Hezbollah invade Israel?

Answer 1
Yes, they can as they have many allies throughout the middle east and Israel does not know where the headquarters are.

Answer 2

There are two parts to that question: 1) Can Hezbollah breach Israel's borders? and 2) If they can do this, can they sustain this breach?

1) Yes. Hezbollah proved that it can breach Israeli defenses when they kidnapped the Israeli soldiers Regev and Goldwasser. This, however, was a coordinated attack with months of planning as opposed to a morning jaunt. Hezbollah needs to use a concerted effort to breach Israeli defenses.

2) No. Hezbollah showed in the 2006 Israeli-Hezbollah War, that Hezbollah is an insurgent fighting group. Such a group can only fight a defensive war, not an offensive one that requires occupation of hostile territory. Hezbollah requires loyal allies to live in the territory to be invaded. Israelis (whether Jewish or Arab) have no love of Hezbollah and this would require the army to fight out in the open where the Israeli army is much more effective. It is telling that during the 2006 Israeli-Hezbollah War that the only attacks perpetrated within Israeli borders were missile attacks as opposed to military raids or direct combat. As concerns Hezbollah's allies, Iran, for all of its bluster, is not willing to expend military troops to bolster the regime of Bashar al-Assad (a regime it still financially backs) while Syria is in the midst of a civil war that Iran could effectively end. How much less is Iran interested in assisting an invasion of a country that has a far stronger military capability and where it has no internal allies.