#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "\/s\d+x\d+\/"
Local $sString = "cd.com/vp/3070d0210e464e/5AEFB3ED/t51.2885/s150x150/24845474_1790806444289980_66798452736_n.jpg" & @CRLF & _
""
Local $sSubst = "/s720x720/"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm