I need a screwdriver.
kach-cha-VEE-teh — four syllables; stress the third. The 'cc' makes a double 'ch' sound.
Use this as your first shopping phrase in a ferramenta. It is a basic request and will be understood everywhere. Specify the type (a testa piatta / a croce) if you know which one you need.
Cacciavite literally means 'screw-chaser'. A testa piatta (flat head) and a croce or Phillips (cross/Phillips head) are the two main types. Many Italian ferramenta staff will ask which type you need if you do not specify, so knowing the distinction is useful.
Un cacciavite a croce, taglia 2.
A Phillips screwdriver, size 2.
Phillips is called a croce (cross) in Italy; size 2 is the most common for household use.
Un cacciavite piatto piccolo.
A small flat-head screwdriver.
Piatto (flat) is the Italian term for flat-head/slotted screwdriver.
Avete un set di cacciaviti?
Do you have a screwdriver set?
Set is used in Italian (borrowed from English); a set comes with multiple sizes.
Italian hardware store owners (ferramenta) are often remarkable repositories of practical knowledge. It is entirely normal to walk in, describe a problem vaguely, and leave with the exact right solution. This consultant-style service is one reason Italians prefer small ferramenta over large chains, where staff may be less knowledgeable.