nte123ap cross reference
You can try the following sites:
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PN100 is ageneral purpose npn transistor whicy you can replace with any other common npn transitor such as 2N2222, BC107, 147, 547, .. , 2N2369..
PN200 as above but pnp; BC557, 2N3906, ...
The voltage regulator, the LP2591, most likely doesn't have direct replacement, and for non-battery application without some of its features you can use LM317L.
Otherwise try MAXIM_IC site for their range of low voltage drop 100mA adjustable regulators..