While testing a script which takes wlan0 up/down, I've discovered that I can no longer access that interface. Example if I try to bring it up:
ifconfig wlan0 up
I get:
wlan0: unknown interface: No such device
BTW this is 13.37 system
The only way I have rectified the problem is rebooting. Is there a more gracious way of fixing this?

It seem your script unloaded kernel module(driver) of that WiFi device, so no network devices was visible to network subsystem. During reboot, kernel/udev reloaded all drivers and so you got your interface. scripts who manage interfaces up/down generally must not to do it via removing unloading drivers.

I do wish UR conclusion were correct but feel that is not the case. The modprobe commands to remove and replace are at the very first of the scrip and were functioning well for several iterations of the script running. Then I was getting a hesitation at that point which got progressively longer to about 5 minutes. I could see something called rescue in the ps -ely listing but my list gets cut off at the right. I was able to kill -9 based on the ps list. Now this occurred previously too.
I have since posting search it further and see that ndiswrapper on other distros have this same problem until EnableAuto...(I forget) is changed from 1 to 0. I looked thru my ndiswrapper files but was not able to grep out that phrase. Hence I am wondering if running with ndiswrapper too many times in succession is the cause or if it is within the ndiswrapper itself. BTW I did a lsmod | grep ndiswrapper when this occurred and it was found. I failed to mention that not knowing its significance at the time.