How could they continue searching for the door to Lot's house, even after they had been smitten with blindness and not relent?
Seforno: There are some Resha'im whose wickedness is so ingrained that they can never relent. 1
As the Gemara says in Eruvin 19a,"'Even at the entrance to Gehinom, Resha'im do not to Teshuvah!"
What is "Sanverim"?
Rashi: It is blindness.
Rashi (Melachim II, 6:18): It is bewilderment. He sees, but does not know what he sees.
Ibn Ezra: It is blindness of the heart and of the eyes. Also Elisha struck the troops of Aram with Sanverim (Melachim II, 6:18).
How could the angels blind the people? This amounts to a second mission!
Moshav Zekenim: This was needed to save Lot, so it is like one mission. 1
Only one of the angels was sent to save Lot! Why does it say that they blinded them? However, also below (19:16) it says in the plural, "they held his hand... they took him out... they left him," and only afterwards, "he said (to Lot)." Refer to 19:12:152:1.
QUESTIONS ON RASHI
Rashi writes: "'Sanveirim' - a plague of blindness." What is Rashi explaining?
Gur Aryeh: Sanveirim is not a weapon that the angels utilized to smite them, but rather an intangible plague.
Rashi writes: "'From the youngest to the oldest' - The youngest began the sin (19:4), so they were punished first." Why explain this way?
Gur Aryeh: We would expect the plague to hit everyone at once, and the verse to say, 'young and old.' Rather, the plague began from the youngest, because they had led the way in surrounding the house.
