Help please me find out what this means
As pointed out, the characters are 天寶紋銀, and are engraved in the small seal (小篆) style.

There are several character components which don't really resemble their regular script counterparts.

天


  「天」 is comprised of
  
  
  「一」(what this represents is disputed, but it is not one in this context);
  「大」(depiction of a person with outstretched arms).
  
  
  「一」is fairly recognisable. A seal script version of「大」is
  
  
  
  which blows up the proportion of the arms and legs.


寶


  「寶」 is comprised of
  
  
  「宀」(depiction of a house/building);
  「玉」, simplified to the component form「」(depiction of jade pieces);
  「缶」(sound component; OC rime: 幽);
  「貝」(depiction of cowrie shells).
  
  
  「玉」，「缶」，and「貝」are all fairly recognisable in seal script. Since「宀」depicted a full-fledged building, ancient scripts will commonly have the sides stretching down to fully depict a building's walls. A seal script version is
  
  


紋


  「紋」 is comprised of
  
  
  「糸」(depiction of silk threads);
  「文」(depiction of a person with an emphasised torso containing markings), doubles as the sound component).
  
  
  
  
  「糸」
  
  The seal script version of「糸」is derived from the original picture, representing several loops of silk threads ending in some frayed thread ends. An oracle bone version looks like
  
  
  
  turning the above upside down directly leads to seal script versions which look like
  
  
  
  Note, the number of thread loops may be variable, and you will sometimes get variants that have three loops instead.
  
  
  
  「文」
  
  The seal script version of「文」is simplified from the original picture, representing a standing person's body with markings (like tattoos) on it. An oracle bone version looks like
  
  
  
  「文」in fact was the original form of「紋」, having「糸」added to it after「文」became exclusively used for the association with the meaning writing. The shape was simplified by the removal of the markings on the torso, and from the above, the similarity to the shape of「大」is not coincidental; both were derived from the shape of a person, while the middle empty space in「文」is just due to the emphasised torso. This leads to the seal scripts which look like
  
  


銀


  「銀」 is comprised of
  
  
  「金」(depiction of a container for melting metals);
  「艮」(sound component).
  
  
  
  
  「金」
  
  The seal script version of「金」is derived from the original picture, which depicted metal plates「冫」formed from a smelting process, represented by a crucible:
  
  
  
  「冫」was later borrowed as a simplified version of「仌」(ice), but the original meaning can still be seen in「冶」(to smelt) and「凝」(condensation/solidification). The markings representing the metal plates were later moved around and more marks got added to or subtracted from these over the course of history, but eventually two marks settled to their current position in「金」.
  
  
  Samples of「金」from bamboo slip writings from the State of Chu. The red box reveals some examples which look like the modern form.
  
  The top of the crucible doubles as a sound component, which is「今」. For reference, bronze script versions of「今」look like
  
  
  
  with a seal script form that looks like
  
  
  
  The above leads to seal script shapes looking like
  
  
  
  
  
  「艮」
  
  The seal script version of「艮」is derived from the original compound, which is comprised of「目」(eyes). The bottom part originally represented a person and looked like「人」or「儿」. 
  
  
  
  For reference, oracle bone versions of「目」and「人」:
  
  
  
  This leads on to a seal script shape (note: see further below)
  
  
  
  Variants of「艮」started changing shape during the Warring States period, leading to the modern form corrupting「目」into「日」and the bottom shape into what it is now.
  
  
  
  Note that「艮」originally meant to look backwards; the highly similar character「見」was originally composed from「卩」, later changing into「止」or「人/儿」.
  
  
  
  To avoid confusion,「艮」sometimes used a shape that looked like「匕」:
  
  
  
  This leads to the different seal script forms
  
  
  
  「艮」vs.「見」




References:


季旭昇《說文新證》
小學堂